On my Windows box I use a mix of 2 anti-spyware apps (Adaware and Spybot S&D), 1 anti-virus (either of the 3 aforementioned but not all at once of course), 1 firewall (my router has a good one built in) and Firefox.
On my Linux box I use.....well, no need for any of that ( still use Firefox though).
The rEVOLution is not being televised