When on XP:
Instant Messengers: Trillian Basic
Spyware / Adware removal: Ad-Aware, Spybot
Internet Browsing: IE 5.5, 6
FTP client: IE 5.5, 6
FTP Server: Good ol IIS
Media Player: WMP9
Music Store: Uh...well does Kazaa Lite count?
P2P: See 'Music Store' -- eMule, Shareaza, Bittorrent
IRC Client: Trillian
Office Suite(Microsoft Office, Start Office): OpenOffice.org
Email Account: gmail
Anti-Virus: Anti-Vir, NAVNT 2001
Firewall: Hardware
When on Fedora Core 1:
Instant Messengers: GAIM
Spyware / Adware removal: Not many spyware apps that affect Linux
Internet Browsing: Mozilla or Epiphany
FTP client: Mozilla
FTP Server: Don't use it on Linux
Media Player: Totem (Hey, it may a video player, but it atleast does MP3s, pain in the arse on Fedora)
Music Store: Isn't Linux about being free?
P2P: Don't use it on Linux
IRC Client: BitchX
Office Suite(Microsoft Office, Start Office): OpenOffice.org
Email Account: gmail
Anti-Virus: Not many viruses on Linux
Firewall: hardware, NAT