Instead of spending money on anti-spyware programs and running free AV and firewall programs. (Methinks Avast! is free but I'm not entirely certain) I would also grab Symantecs combo packages and just simply supplement them with Microsoft Beta and Ad-aware.
Thats the advice of someone who is equally as paranoid, well you could always just install a linux box and write up your own proxy firewall but people tend to go for the much easier option.
Seriously, a reputable firewall and AV program will always do the job. You can never stop viruses from getting into your PC, its a bit like saying I'm not going to get hit with the flu this winter. Its just wishful thinking, but by regularly scanning and updating your system and staying away from file sharing programs, questionable websites and dodgy attachments it certainly makes life a lot easier.
However for best anti-spyware I for one really look forward to the released Microsoft software. I've been toying with the beta software both at home and in the workplace, when no one is looking.
And currently thats my pick of the litter without a doubt...
