Agardengirl, which free scan did you use? And what viruses did it say you had? What folder in the hard disk did it say they were?
Some of the less reputable online virus scanners will "suggest" you have a virus and then ask if you want to buy their product to clean it out.
Are your AVG, Ad-Aware and Shredder definitions uptodate? If so, then I would imagine AVG would pick up most viruses. You may want to download and install Spybot Search & Destroy, and SpywareBlaster, and when installed, open them, update their definitions and run them to make sure.
When was the last time you did any computer housekeeping? eg, diskcleanup, (Start > Programs > Accessories > Diskcleanup), and Error Checking, (also called ScanDisk on pre XP Windows), and Defrag?
Do you keep your Windows uptodate with critical updates?
My computer is really slow today so I did one of the free scans...it said I had two virus's but this scan does not fix them...I ran my adaware, schredder, AGV scan and they all come up with clean. What do I do next, just leave it or try to find something that will do a better, more efficient scan. Help please.