Well.. u need freewares or paid ones ?
1. MS Office / Star Office or even open Ofice will do
2. Avast Pro / KAV / Norton / Macafee ...
3. Zone Alarm / Sygate Personal / Jetico (Batty...)
4. GIMP / Photoshop (NOTHING BEATS IT)
5. A Burner - Nero mostly
6. A Media pack - Klite/fffdshow
7. A Media Player - Winamp and PowerDVD
8. A pack of jokers oops I mean Browsers - Firefox and Opera mostly
9. A P2P s/w - BC or LW
10. A good game
11. An Extraction Utility - WINRAR prefferably
12. A Messenger perhaps - MSN and Yahoo or Gaim
13. A photo manager - Picasa...
Depends on ur usage ...