High time for the Klingon solution. Accept no compromise. I would have chosen it already earlier. When nasty stuff has hit you once, you never can be sure you really got rid of it after you are finished with your repair - and every Windows repair is just improvisation. Time passes by, you invest trust, make backups of your working files - and they all get infested in the background.
And DO NOT trust into free scanners only, but use a payware solution, the full package, make it a solid one. I have learned that lesson myself just before switching systems:
http://www.subsim.com/radioroom/showthread.php?t=180346
Neal brought it to the point in there:
"Sticking with pay/premium anti-virus software here. I cannot imagine some free AV group has the same resources as Norton or McAfee. If they're not brining in real $$ to pay employees and stay on top of emerging threats, how secure can it be? You get what you pay for. "
Avira Premium for example does not leave you any need to run Spybot. It includes what Spybot does - and then so much more.