I'll take a page out of Warez Monster's book and give you advice he game me. It works like a charm. This is very brief and Warez could explain it better than I could but it's generally the idea.
I don't know what OS you're running but if it's XP, delete the prefetch folder. go to start>search files and folders>push all files and folders on the left and then type in prefetch. Push enter. When the folder shows up delete all the contents inside the folder, they'll show up on next boot when the processes take place again. He talks about deleting TIF's and such but personally I have no problem with removal even if I don't do that step.
For spyware, I use:
Spybot Search & Destroy
AdAware SE Personal
XoftSpy (cost's money unless you have alternate sources)
Spyware Doctor (also costs money)
after you install the 3 programs that don't cost any cash, update the definitions while you're still connected to the internet. Usually an option will be available asking you if you want to update definitions while you're installing the product, of course accept this option. Run all three programs (separately usually because if all three are running, it will hinder performance.) After they are all done, be sure to remove everything they find. You're also going to need an antivirus to detect any possible threats to your computer. I personally use NOD32, but it costs money. AVG Free Edition is a great anti-virus and I would definately recomend it. Before you shut down the PC, go to start>run>then in the box type in msconfig. Go to the startup tab and deselect everything accept for the AVG anti-virus. Download a program called MSconfig cleanup and the list of all the deselected items will appear when you start the program. Push select all and then clean all of them up.
Shut down the PC and when a screen pops up on boot that says at the bottom, press F8 for more options, press F8 and choose safe mode. When you enter safe mode, provided you already deleted the prefetch folder before you shut down the PC, run the progrmas again and once again, delete all files they find. Shut down and reboot.
When you reboot, to be safe, run the spyware programs once more to insure that all bad files have been removed, then run a full In Depth analysis on AVG anti-virus. When it's done, it will tell you what it found and if some files could not be deleted. If some files could not be deleted on either the spyware programs or the anti-virus, I believe it will ask you if you would like to run a scan on the next reboot, push yes. When all files have been removed, reboot to insure that they will not have any chance of coming back.
Warez if I forgot anything and you would like to add/correct me on anything... please feel free. I'm learing this stuff also.