Download
Hijackthis. Restart into Safe Mode, run the program, save a log, and post the log here. While we're perusing the log, download
Spybot &
Ad-Aware. Install and update both in normal Windows mode. Restart into Safe Mode. Run Both programs (choose full scan in Ad-Aware).
Once you've posted that log, we'll have a much better understanding of what's starting up on that machine.
There's a whole lot more to it than that, but without someone actually being there, you'll never get rid of everything 100%. I also recommend investing in a decent anti-virus program. Kaspersky, Nod32 and BitDefender are rated as the top 3, so any of those should do the trick. If you've got something like Norton (especially Internet Security) then the
first thing you should do is remove it. That alone will slow down your machine more than an army of spyware.