actually, to get a really nice setup up, you dont need to torrent anything:
AntiVirus: avast! home edition (free) works really well:
http://www.avast.com/eng/avast_4_home.html
Firewall: zone alarm, free edition. probably one of the best firewalls out there:
http://www.zonelabs.com/store/content/c ... opnav_zaav
spyware: spybot search and destroy, amazing program (free):
http://www.safer-networking.org/en/download/index.html
registry i wanted a free registry cleaner, and apparently windows developed one back in the day. works great, free, and its changes are very easily reversible. simple, right to the point setup. 5/5 stars from me
http://www.download.com/3000-2094-881470.html
additional secuirity: process guard, great program, i always have it running. protects your OS + procceses (probably more) from malicious activity. (free)
http://www.diamondcs.com.au/processguard/
not sure if youll get any conflicts from this setup with genuine windows.
ive been using this setup for a long time now, never had any problems at all. hope that helps
edit: added process guard