Here I made a little list that you can try if you really need that little something that can make your PC move faster:
1. Use Readyboost (if you run Windows Vista), a tool that let's you add more memory to your PC using your memory card or USB flash drive. Good if you have a memory card/flash drive that you don't use at that moment (also you can set how much of the space available you want to use to speed up your computer) Read more
2. Buy more Memory. This one is maybe the best thing you would want to do if you really want performance. You might say why because I already have Readyboost? Yes but Readyboost uses your memory card/flash drive, you USB port (or your memory card reader) and many people doesn't want to go with Readyboost because they consider it doesn't improve your performance as a memory card does. To run Vista you need a minimum of 1GB RAM but I recommend you something like 1,5GB or even 2GB of RAM
3. Upgrade your drivers. Using the latest software for your hardware could lead in better performance most of the time.
4. Overclock your computer. This one is for advanced users. You can add more performance by stressing your hardware to work to it's best. Note that you can shorten your hardware life or even damage it if you make a stupid move. Read here
2,3 and 4 also work with other Operating Systems!