I don't think bolding every single word is necessary.
1) Download and give SpySweeper a try. Also download the free versions of SpyBot and Adaware SE. Scan with all 3. As has been said, SpySweeper does a good job keeping crap off the computer once you clean it up
2) Get a decent firewall, ZoneAlarm is fine for your average user.
3) Get a better AV. Kaspersky has the best overall detection for baddies with the extended database including adware, malware, pornware, dialers etc...
4) User safer browsing habits and update your OS.
5) Don't open shit from untrusted sources.
P4 2.6C, Thermalright SP94/Panaflo 92MM M1A, IC7 Max3, Swifty MCX159, 1GB Geil PC4000 Ultra Plat, Radeon 8500, Audigy 2, 2X WD Raptor RAID 0, WD 250GB SE, Plex 708A, 166SDVD, LianLi PC75, XP Pro.