here is a computer I picked out, fully customizable so mix and match to whatever fits your budget.
http://www.shopping.hp.com/webapp/shopping/computer_can_series.do?storeName=computer_store&category=desktops&a1=Usage&v1=Everyday+computing&series_name=a1620y_series
Adaware SE personal, Spybot S&D, Spyware Blaster, Spyware terminator, Avast Anti-virus, Comodo Firewall.
Thats basically everything I have on my computer, works pretty well for me for being completely free.
I remember I accidentally clicked on the AOL thing on my desktop a few years back, somehow they got our credit card number and started charging stuff, of course we put a hold on the card and called up one of there representatives. AOL sucks...
just be careful about what you download, I have been using limewire for 2 years and have had no problem what so ever, just do a virus scan and spyware scan after downloading, and make sure you scan the files that you downloaded before sending it to my documents or where ever.