When I must use Windows this is my list for my top GNU solutions. This set of tools make my Windows experience much better.
- 7-zip - Archive manager that kicks WinRAR's butt 7 days a week.
- Cygwin - I just have to have my BASH shell and Perl at all times.
- Notepad++ (Notepad Plus Plus) - It takes the pain away from dealing with (Note|Word)pad.
- Wireshark - Formerly Ethereal. Yeah I'm a packet head.
- Snort IDS - Snort can be a packet head's best friend.
- Mozilla Firefox - I'm typing this in it right now.
- NoScript - "Hopefully" keeps my (browser|Mac) from getting 0wn3d.
- VLC - Highly compatible video player