Vista comes with all sorts of changes from the Windows XP interface - and I guess we're going to have to get used to it eventually. Here is a handy list of things you can do if your Vista machine starts slowing down.
If you're not sure exactly how to go about any of the following, this Vista tips page might prove useful.
Delete programs you never use
Quite often our computer comes with a software bundle, including programs we never use. I also tend to experiment with programs and then end up never using them. Even if we are not using them, they might be quietly working in the background. Uninstall any programs you never use.
Limit how many programs load at startup
Many programs are designed to load up automatically at start-up. If you don't use them, or commonly don't use them straight away, they are wasting resources.
Clean up your hard disk
The disk clean up routine will remove lots of little temporary files that tend to accumulate on our computer.
Defragment your hard drive
This will improve file accessing and load times.
Run fewer programs at the same time
This will keep more RAM memory available for the task you are currently running. If you have too many programs running at the same time, you can exceed the RAM available on your computer and processing will start using the memory swop file on your hard drive which will result in a drastic drop in performance.
Turn off visual effects
All that fancy fade in/fade out functionality is drawing on resources. If you're tight on available memory - lose the fancy effects.
Programs don't always close down as cleanly as one might hope for. Don't just leave your computer on for weeks at a time. (Eskom is probably helping you out with this one just at the moment )
Add more memory
If processing has slowed down dramatically, you might be into the swap file. Add more RAM to keep everything in "instant memory."
Check for viruses and spyware
Our worst nightmare. And they can be a real resource hog too.
Check your computer’s speed
Vista has a tool called the Windows Experience Index. This measures a number of hardware and software elements to give you an idea of how your PC is performing.
Disable services you don’t need
Windows runs many different programs in the background - you might not need them all running. One for the experts only!
There are even more Vista performance enhancing tips here.