Couple possibilities off the top of my head. Have you got anything in your cd drive or your floppy drive when my computer is taking forever to load? Frequently a poorly burned CD will cause issues like this, as my computer tries to read the cd and will just sit there waiting until it does.

Another possibility is that it's your virus scanner. Ironically, you'll often get far better performance out of a virus infested computer than you will out of a computer with a virus scanner constantly running. If your virus scanner is on, try turning it off. It'll probably have an icon in the bottom right corner of your taskbar if it's one of the constantly running types.