Just because your computer is playing up doesn't mean it's time to throw it away. Toby Green discovers five easy and inexpensive ways to restore old machines to their former glory

It costs hundreds of pounds, but your PC may have a suprisingly short life. Fresh out of the box, it runs like a dream, but after only months of use, it can become frustratingly slow. It takes ages to start up, browsing online becomes tortuous and running multiple programs at once is impossible. Plus, it could begin crashing with alarming regularity.

In more financially stable times, we might have simply bought a new computer, but this has become less attractive as household budgets tighten. There is an alternative though; perform some simple tasks and install a few upgrades and you could get your PC firing on all cylinders again.

Have a clear out "One simple task is to tidy the hard disk," says Paul Allen, editor of PC magazineComputeractive.

There are two Windows utilities that Allen recommends. The first is the Disk Cleanup program, which prompts you through a series of steps to get rid of computer clutter, such as desktop icons for programs that you don't use. The next is the Disk Defragmenter – this organises the data on your hard-drive so the computer doesn't have to work hard to access it.

Another easy task is to fully delete any installed programs that you don't need. "These eat up hard disk space and slow down the speed at which Windows starts," says Allen. "Check the list of installed programs in Windows XP by clicking the 'Start' button, opening the Control Panel and selecting 'Add or Remove Programs'." In Vista, open the Start menu and type "programs" into the search bar, then select "Programs and Features". Go through the list and select the programs you no longer need for removal."

Just don't be too gung-ho. "If you don't recognise a program, leave it be," warns Allen. "Windows and security applications store updates here and these shouldn't be removed."

Smarten up your security

If you feel your computer slowing down, this could be a sign that it has been breached by malevolent forces. "One of the symptoms of becoming infected is that your system starts to go down," says Con Mallon, a director at Symantec, producer of Norton security software. "It has a split personality where it's doing the things you want it to, but it's also doing what the hacker or the malware writer wants it to."

Running a virus scan regularly should pick up any nasties, but run the updates program so it has the best chance of detecting every virus.

"Anyone using a Windows PC online should have an anti-virus tool, firewall and anti-spyware utility," says Allen. "You can get all three for nothing." He recommends AVG Free ( free.avg.com ) or Avast ( www.avast.com ) for anti-virus; the ZoneAlarm Free Firewall (you'll need to disable the Windows version); and, for an anti-spyware program, Ad-Aware Free ( www.lavasoft.com ).

Boost your memory

The amount of memory your computer has isn't only about the number of photos or songs you can store on your hard disk. Alongside that you also have RAM (random access memory), which is used by your computer temporarily while it is running programs.

The more RAM you have, the more programs your computer can cope with running. "Adding more memory is one of the best ways to boost a PC's performance," says Allen. "The more memory, the better, although the standard versions of Windows XP and Vista have an upper limit of 3GB. www.crucial .com/uk and www.kingston.com/tools can tell you how much memory your PC can handle and what type to get."

Prices vary, but you could pay as little as £15 for 1GB of RAM – in terms of a minimum to aim for, Microsoft say Windows Vista can run on as little as 512 MB, while GB would provide optimum performance.

As well as being good value, extra memory is also easy to install yourself, though any computer store can do it for you. As long as you have the right memory for your motherboard, it should be a case of popping the old memory out and slotting the new memory in www.computeractive.co.uk has tutorials for desktops and laptops.

Let a program do it for you

There are a huge number of commercial programs that claim to clean your machine at the touch of a button. One area where they can help is the registry – where settings for everything in your computer are kept. It is so important to the running of your computer that you should never attempt to edit it yourself unless you're 110 per cent sure of what you're doing.

But some of the tasks that these programs do you may find you don't need. "System clean-up utilities are ten a penny and we've found that many of them simply automate tasks home users can perform," says Allen. Not all of them have to be paid for – Allen recommends CCleaner ( snipurl.com/ ba4ln ), which includes a registry cleaner.

Before you buy or use any program do your research – with so many available you need to be confident that what you use won't damage your PC, so go for a big brand or something recommended by a reviews site you trust. Make sure your registry is backed-up before editing it, even if you're confident about the program you're using – Microsoft's Help and Support website ( support.microsoft.com ) gives a step-by-step guide.

Call in the experts

If you don't have the time or confidence to mess with the inner workings of your computer you may decide to call in the experts. There are independent computer shops and numerous high-street stores you can bring your PC in to, while many offer home-visits.

Tim Fairs of TechGuys, the technology experts who offer their services in branches of PC World, says that such a service can give you peace of mind. "You get the plumber to come round or hire someone to service your car. I think the same these days is true of technology in that a lot of customers would much rather have someone else do the work than take the risk."

Of course, this all costs money and Allen believes it's often unnecessary. "Everyone should at least give it a try themselves before paying for a homevisit or in-store service."

However, if you are unsure in any way about what you're doing, always consult an expert first.