Just out of intrest, how much RAM does your computer have? If you right click on My Computer and then click propities it will bring up a window. Down in the bottom of this window it should say x amount of RAM somewhere.

Any less than about 256MB and this is proberly a major cause of the slow down.

EDIT: Oh and one more thing, try holding down left shift from when you log in(if it automatcially logs in, do it when it says "loading your personal settings") till when it has finished loading everything. What this does is bypass loading all things at startup. So if it improves it a lot, then you can look into removing some items that startup.