Secunia PSI. It helps you keep your programs up to date, which makes your PC less vulnerable to attacks.

ESET NOD32 antivirus, cause it behaves so nicely (it's not free though).

Firefox, cause I'm used to it.

CCCP + Media Player Classic for videos, because i think VLC's icons are ugly.

Winamp for music.

mIRC for my IRC chatting needs.

I use WinRAR for archiving.