I use three tools to keep my windows patched/updated:
- apup[1], faster than windows update;
- sumo[2], to have latest versions of your installed programs;
- secunia PSI[3], personal security inspector, to know if your programs are exosed to risk(s).

Your default installation should include an Antivirus, antispyware and a sandbox (sandboxie[4]) to play with untrusted applications.

Links:
[1] – http://www.autopatcher.com/forums/index.php?showtopic=89
[2] – http://www.kcsoftwares.com/?sumo
[3] – http://secunia.com/vulnerability_scanning/personal/
[4] – http://www.sandboxie.com/index.php?DownloadSandboxie

Have fun!