There is a chance your comptuer would be slowed down by a lack of hard drive space, your computer uses free hard drive space as something called a swap file. Think of it as RAM (you probably have 128, 256, or 512MB of it) on your hard drive. The amount of hard drive space your computer allocates as swap space is inverse to the overall power of the computer. If it's an older one it will use more than if it's a newer one. Try deleting your temporary internet files in IE, if you've never done that before it could get you a couple hundred megs or more. Try to get yourself around a gig of free space and I bet you will see (at least some of) your problems melt away. Delete some files you don't use anymore, or invest in an external hard drive and move some of your data from your current hard drive to the external one.
