• Offline Files: Useful if you synchronise files between computers, but we don't.

• Tablet PC Input Service: This isn't a tablet PC.

This recovered perhaps 10MB of RAM. Prune your services more severely and you can achieve more, but you're also risking problems if you remove something that you actually need. If you're willing to take the risk, then visit Black Viper for detailed guidance.

3. Reduce hardware requirements

If your PC has 4GB of memory you'll probably find you can only access 3 to 3.5GB of that, because your BIOS has allocated the rest of the address space to your video adapter, network card and so on.

To see what's allocated to hardware on your PC, launch Device Manager (click Start and enter devmgmt.msc), click View > Resources by type and expand the Memory section. The real resource hog will probably be your video adapter. If you've a high-end 512MB graphics card, say, then that's going to grab 512MB (and more, actually) of your address space. This probably won't matter if you've 2GB of RAM as there's no memory there to be blocked, but if you've 4GB then it'll prevent you using it all.

You can't make this problem go away entirely, but there are ways to reduce its impact. Have you installed an expansion card you no longer need, for instance? Remove it. If you don't make use of a high-end video card then consider a downgrade to one with less RAM (128MB is enough to run Vista). And explore your BIOS setup program to turn off features you don't need. There's generally a menu called something like 'Onboard Device Configuration' or 'Integrated Peripherals' where you can disable onboard graphics, integrated sound, unused network adapters or IDE channels and so on. Use this to turn off surplus hardware, your BIOS won't allocate it any resources, and more of your 4GB RAM will be left for you.

4. Turn features off

Don't enable Windows functionality unless you actually need it - there's almost always a performance penalty.

To speed up Windows Vista, for instance, turn off the Aero interface if you can do without it (right-click the desktop, select Personalise > Theme and choose Windows Classic). Your desktop won't look nearly as pretty, but as compensation you'll save close to 40MB of RAM.

And is it really important to see the Windows Vista network icon flash as data is transferred? If not, right-click the icon, select Turn Off Activity Animation and save 1 to 5MB of RAM.

5. Run Explorer efficiently

Windows Explorer can run each Explorer window in a separate process, so if one window crashes then it won't bring down the others. Sounds reasonable, but in our test it uses at least an extra 10MB of RAM for every Explorer window you have open. If Windows keeps crashing then it's better to find why, turn this feature off and reclaim the wasted memory. Click Tools > Folder Options > View, scroll down and make sure 'Launch folder windows in a separate process' is not checked and click OK.

6. Minimise applications

If you're running an application then it'll inevitably consume RAM, but there's a way to reduce the amount: minimise it. If the app isn't doing any work (it's just a browser with several tabs open, say) then when it's minimised Windows will reclaim some of its memory to give to other applications. So it's always preferable to minimise inactive programs rather than just leaving their windows open on your desktop.

7. Avoid dubious tweaks

Don't waste your time on pointless memory-related tips or programs that either don't work or only make things worse.

Some sites recommend an 'AlwaysUnloadDLL' Registry tweak that supposedly tells Windows to unload DLLs as soon as the program using them closes. But it doesn't work in XP or Vista. Others claim that setting a Windows XP Registry key can enable the Superfetch, the Windows Vista caching system, in Windows XP. It's a myth. And the web is crammed with RAM 'optimisers' that make big promises, but they can't fix memory leaks and don't 'free up' RAM (in fact they'll only consume it). Don't be fooled. See TweakHound for more 'Bad Tweaks'.

8. Monitor your PC

Once you've cleaned up your PC, reboot and take a closer look at what's using your RAM right now.

Press Ctrl+Shift+Esc to launch Task Manager, select the Processes tab, click View > Select Columns and make sure 'Memory (Private Working Set)' is checked). Click OK, select the 'Show processes from all users' button, then click the 'Memory (Private Working Set)' column header.

You'll now see every process on your system, in the order in which they're using memory. Browse down the list - are you running any background programs that you really don't need? Turn them off if so. If you discover some memory hogs you don't recognise, then enter their process names at Google to find out more.

If you really want to drill down into your PC's activities, then there are two free Sysinternals tools that will prove invaluable. Autoruns will show you everything that loads when your Windows starts up, while Process Explorer displays running programs in great detail and shows you the resources they're using. Go download them, they're some of the best PC troubleshooting tools around.