One way to easily speed up Windows 7 is to add a USB thumb drive or SD card to your machine. You should get a pop-up window that asks if you want to use part or all of the device for ReadyBoost. If you don’t get the pop-u, right click on the SD card in Windows Explorer and choose Properties and then ReadyBoost. I usually max out the possible memory to the allowable max of 4094MB.
How much it helps seems to be up for debate, but you’ll probably get more help if you’re computer has a minimum of memory and probably very little help if your computer has 4 GB+.
(Note – Sept. 2011 – just watched Tekzilla and they basically said the same thing. If you already have 4 GB memory – don’t bother.)