I’ve yet to meet a user who doesn’t want a faster computer. Being able to speed up a computer for a minimal amount of money is even better. A new technology was introduced in Windows Vista (also in Windows 7) called ReadyBoost that allows you to use portable flash memory storage to boost the speed of loading applications. You can use USB flash drives, the cards you typically use in cameras and more with ReadyBoost. If you want to implement it, I recommend you read the Wikipedia page on ReadyBoost and follow the links in the article for instructions.
One downside is that ReadyBoost doesn’t exist in Windows XP. Those who want to use it on Windows XP should look at eBoostr. Users of Windows Vista and Windows 7 should also give it a look as it can provide better performance than ReadyBoost. There is a free trial version so you can test it on your system before buying. Different versions are available for $19.99-$39.99 depending on what features you need. The only other cost is for the flash memory device. You may already have one around that can be used. If you want more speed, this is definitely something you should investigate.