Imho Spyware scans are all good and all, but not really efficient anymore. Most of today's spyware evolved into one of two modes: Extremely annoying, blocking EVERYTHING from starting [See Antivirus 2009] or stealthy, in fact so stealthy - neither you or any antispyware app would ever detect them since they changed the core of your windows os (aka kernel) so basically becoming part of it - so Trust me, save yourself a lot of headache, money and trouble.
Backup all you important files, Find original System restore and do whole pc wipe and restore to original state...
This is basically what Best Buy's Geek Squad would do anyhow, but charge you $300 for this.