Windows 7 Forums have a new article featuring 19 ways to speed up Windows 7. Some of these are simple tweaks that you can perform in a few clicks, others require a more advanced understanding of the OS:
"Microsoft Windows 7 is already a much more responsive operating system than its predecessors, but there are tweaks and changes you can make to speed up Windows 7 even more. By reading this list and implementing some of the suggestions, you can increase performance in a very short period of time. If you have any further suggestions on how to improve the speed of a Windows 7 PC, please let us know in the comments section so that we can keep updating this list."