Good question,

I run Norton Anti-Virus
and:
1. Disabled NetBios over TCP/IP

2. Disabled Client for Microsoft Networks

3. Disabled Universal Plug and Play

4. I use Outpost Firewall

5. I also use a router

6. Disabled File and Printer Sharing

and I use Ad-aware and considering on using another program to safely overwrite any files in my recycle bin...and I never keep any personal stuff in my pc's hard drive, such as my social security number etc..