What are the best free virus scans/spyware detectors available online?

[Aypapi]

I have a piece of adware on my computer that I obviously wish to get rid of (it slows down my computer... -.-). Avira Free Version is a perfectly fine antivirus program, but apparently it does not have this (insert obscene adjective here) adware on its detection list. I looked into this adware a bit more and found that AVG should have it on its detection list, which would mean a for me and a for the adware... elimation of the adware in other words. There are several problems with this idea, though. 1. I am not sure about this, but I believe I read somewhere that having multiple AVs (AntiVirus) may cause confliction between programs... is this true? (read titular question for the specifics) 2. Supposing that the above question were answered with a "Yes", I would have to remove Avira. I have also read that this action is difficult to fully complete... is this true and if so, how would I go about screwing the adware (FYI it is called WhenU SaveNow, and it is despicable in my personal opinion)? 3. Should someone else incidentally have this (virus? adware? program?)... thing... and have successfully removed it, could you answer back with your solution? Notes about the *censor*ing software... I am aware that you (ahem) should (ahem) be able to remove the "thing" (I refuse to name it except in an above example) in Windows' Add/Remove Programs panel. It is not a part of the list of removable items, so I assume it must have latched onto a download (silly brother >:O). Because my computer is second-hand, it has a variety of rather shifty programs (in my paranoid opinion). Flock I think is decent, Limewire... not so decent, my idiot brother's downloads off Limewire... VERY untrustworthy. However, the adware might have been present before that bozo downloaded Limewire, so I can't fix the blame on Limewire. Also, this adware updates itself and seems to "read" the ******* on the web pages I browse and display related *******... fortunately, it does not understand Mandarin. The adware PHAILS (phails, fails, same thing) in that it displays its unconvincingly poor "Click me" (the "click me" idea is displayed in many ways...) ideas in Internet Explorer while I browse in Mozilla Firefox -.- Any solution would be welcome. forex robot