Browser - Mozilla + Privoxy combo with java switched off, sites not to install software and cookies only for originating websites and only for the session. IE is only used as back-up when a website refuses to work properly and then all active x is set to disable/prompt, software permisions to high, privacy set to medium high with pop-up block enabled.
Scanners: Ad-aware, spybot, ms antispyware (with guard up), ewido,a-squared, cwshredder, bit defender free as on demand scanner (disable automatic start up with windows to free system resources). Also anti-vir can work as a stand-alone scanner. Otherwise I just have AVG guard running day to day for it's low system resources (as I didn't like the constant activity through my firewall for anti-vir control prog to communicate with its guard program) and I can live with it's generally poor detection rates because the other aps/setup can make up for where it falls down while it maintains a good enough detection rate for dos, windows and macro viruses which are of most immediate importance for me.
Prevention: Microsoft update, limited accounts, spyware blaster and the immunize function of spybot, and a software firewall (either Zonealarm 5.5.094.000 or Kerio 2.15) and a hardware firewall if possible (router or spare box set up as such). Also Peer guardian has a function to block out ads and spyware companies connecting to you.
Used together properly, you get a pretty good setup which because of not many active programs running means plenty of free system resources while having plenty of scanning capability as backup if something does go awry.
Check-up: trend micro's house call (although I have got a few false positives with them) along with Kaspersky's online scan.
Best paid for software would be spywaresweeper, spywaredoctor, kaspersky(! - by a mile). However, with a similiar setup to the one above I really doubt you'll need it - it could even be a challenge to pick up nasties while going to a warez site. Ultimately, you only need pay for programs if you are trying to make up for some very bad internet habits - email attachments, warez/'other' sites, unthinking P2P downloading (as gangs often crack them and then add a trojan or a worm)
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