I plan on switching to an iMac in the next month or so and would like to know which is the best comparable software?

Audiograbber (Something that can use Lame)
AVIAddXSubs
CCleaner
Damn NFO Viewer
Iconworkshop
mIRC (Colloquy looks good)
Mediacoder
Mozbackup
MP3 Tagger/Renamer (I'm currently using Morgoth)
QuickSFV
Perfectdisk
Sound Forge
VirtualDub
WinRAR

CCleaner - AppZapper
mIRC (Colloquy looks good) - ColloQuy
Mediacoder - Handbrake
Perfectdisk - OnyX
WinRAR - RAR Expander

Audiograbber (Something that can use Lame) - max
CCleaner - onyx
Damn NFO Viewer - textedit
Iconworkshop - icon composer, iconbuilder
mIRC (Colloquy looks good) - limechat, colloquy
Mediacoder - visual hub, ffmpegx, max, audialhub
MP3 Tagger/Renamer (I'm currently using Morgoth) - simple tagger
Perfectdisk - not needed
Sound Forge - amadeus pro, sound studio, logic
WinRAR - unrarx, betterzip, unarchiver