Start > Run > cmd.exe, type cd "%systemroot%\downloaded program files" press enter and type dir. If you see any suspect file look it up on Google and see what it is, some malware uses random names so then you will be out of luck. Delete files with the del command, i.e. del file.ini

Another good program they not mention is BHODemon, it lists the Browser Helper Objects installed on your computer and will warn you if you let it run when a new BHO is installed. This way you can easier get rid of the spyware since you know it's real name and can Google up the information.

Pestpatrol has a great resource of info on how to manually remove spyware, they also have an online scanner but it will not let you remove anything, to do so you must buy their program. I have never used it and can't comment on if it is good or not, but the article linked above plus my recommendations should get you a long way on the go, else there is always our forums where you can ask for help.