In the past, the only way to speed up your computer was to get a more powerful CPU - the microprocessor or "chip" that is the brain of the machine. Now you have to be subtler: the trick could well be to combine a faster processor with extra memory.
Until last year, upgrading a processor involved replacing the complete motherboard, which includes a plethora of additional components. A new Pentium motherboard would cost at least pounds 250. But in 1995, Intel, which makes the PC chips, introduced a new type of "Overdrive" chip that can be slotted easily on to the motherboard, which should allow you to upgrade your 486 to a faster version, or even a Pentium. These chips cost from pounds 80 for a faster 486 to pounds 180 for a Pentium.
The arrival of Windows 95 and other "fat" software has meant there has been massive demand for chips that increase random access memory, or RAM. These chips are expensive (it can cost at least pounds 100 to upgrade from four megabytes to the eight Windows 95 needs), which is why they have been a prime target for thieves.
This means you should be careful who you buy from, and avoid bargain- basement offers: the market rate is pounds 25 to pounds 30 per megabyte. The memory supplier Datrontech guarantees new chips with parity checking and serial numbers. Also, keep an eye out for cache chips, a special type of memory that holds the most recently used instructions, increasing speed appreciably.
In recent years the process of fitting new RAM has been simplified greatly. Your PC is likely to have free slots into which you simply push the new chips; this might mean discarding existing memory chips to make room, but as these retain a resale value, your original investment has not been wasted.
What if it still feels slow?
In that case, you have hit upon one of the most overworked parts of your computer. Much of the computer's work involves no more than pushing pictures around the screen. For example, not only does a Windows 95 machine have to copy a file from A to B, but it also has to draw a 20-frame animation of a flying piece of paper. It comes as no surprise, then, that the happiest users of the new system are those with fast graphics cards. Every PC will have some kind of graphics board, but you can buy "accelerator" cards with specialised chips to speed the commonest tasks - opening and closing windows, for example. They start at pounds 100. The more memory a card has, the more colours can be displayed: 65,000 "High Colour" is possible with 2Mb, and more than 16 million "True Colour" with 4Mb, although only a graphics expert will be able to tell the difference.
Will I have faster Internet access?
Salesmen have used the lure of the Net to sell bigger machines. But the speed of any online service depends almost entirely on the capabilities of your modem. Certainly, more memory helps to run the newest, flashiest versions of the Netscape World Wide Web browser, and is almost mandatory for the Microsoft Network, but the throughput and decompression ability of your modem is paramount. Remember that the standard modem is V34 capable of 28,800 kbps speed.
The market for such devices has been shaken up by the arrival of Phillips' first offering: a user-friendly 28.8k device retailing at around pounds 150. Other manufacturers are sure to follow this lead. It will probably be the last modem upgrade you will ever need: standard phone lines can't carry much more data, and mail-order retailers such as Powermark are poised to bring digital ISDN lines into the home.
One very cheap upgrade for older machines is indispensable for a Net connection: a fast serial port, known as a 16,650-type chip. Many older machines have a primitive and unreliable connector as default, which severely taxes the computer's main processor. For about pounds 25, a 16,650-type chip permits not only faster speeds, but also greater reliability, with less of the "stalling" with which Net surfers are familiar.
I've run out of disk space. What shall I do?
If your PC isn't Plug and Play compatible, fitting a new hard disk is likely to be the most painful of upgrades.
Both choosing and fitting a new hard disk requires some technical knowledge, and a lot of tinkering. As well as adding the new disk, an additional controller card may be needed. Worse, crammed cases rarely accommodate an extra disk and its cabling with ease. The combination of disk and a fresh controller, however, is likely to improve performance, particularly if they use enhanced EIDE technology, or if the system has a spare "local bus" slot - the wide-bandwidth connector on your machine.
Surprisingly, the market has been slow to appreciate the complexity of the process and introduce out-of-the-box packages of disk, card, cables and instructions in the way multimedia bundles are marketed. Maxtor is one exception; otherwise the components arrive raw, usually without even screws.
Fortunately, this is only one part of the story. Yesterday's industrial back-up software is being transformed into a flexible and friendly storage option that could do away with the need for a new hard disk. Iomega's removable Zip drive plugs into the computer and acts as a giant floppy disk drive. The Zip offers 100Mb of storage for a tenner. It is an attractive and thoughtful package: chunky yet light enough to carry. The spring will see the launch of a high-end Jazz drive, with 1Gb disks available for around pounds 100.
What about multimedia?
The best way to convert your computer into a multimedia machine is to buy a kit containing a sound card, CD-Rom and speakers. Creative Labs leads the way with two outstanding bundles. Its three packages are aimed at general-purpose home-users and game-oriented users. Aztech, meanwhile, offers good software, while Sony has a well-engineered option. In each case, a four-speed CD-Rom is the standard.
While Creative Labs' basic SoundBlaster 16 is still recognised by nearly all PC games, many have synthesised effects targeted at a different card, the AWE-32 card. In each case, check that the latest "drivers" are available, either from the supplier or off an online service such as CompuServe. Without these tiny pieces of software, the system won't be able to recognise the new peripherals. Windows 95 drivers seem to be particularly scarce.
Definitions: things to buy, make bigger and speed up
Microprocessor: often referred to as the brain of the machine, the "CPU", or simply the "chip" (although there are actually dozens of chips in the box), it dictates the speed of the machine. A faster chip can perform more instructions, and can in theory do the same work faster.
Hard disk: the fixed disk on which the computer's programs and data are held.
Memory: Silicon Random Access Memory chips allow information to be held in an electronic form that can be accessed rapidly. With insufficient RAM, the information has to come from the hard disk, which is much slower.
Multitasking: this takes advantage of the speed of the chip to swap between two programs at once so quickly that it appears as if both are running at once.
Peripherals: any hardware that plugs into the computer, such as a printer or modem.
Disk doublers: software utilities that squeeze more data on to a hard disk by using compression techniques.
Plug and play: a recent innovation in the PC world - although standard on Macs and most other computers - in which the system automatically recognises its own "limbs" or peripherals.
Shareware: software that can be downloaded from the Internet or another offline service. You can try it for free, usually for 30 days.