The most POPULAR software for removing DRM protection:

WM RECORDER
the easiest audio/video stream ripper

WM CAPTURE - Super high quality on-screen video recorder.

SOUNDTAXI
remove DRM protection from Windows Media, iTunes music and video files

Other RECOMMENDED software and services:

• AUDIO/VIDEO STREAMING CAPTURE SUITE
  the best audio/video stream recording/capturing bundle
• REPLAY MUSIC
  the best streaming music recorder
  
  
• REPLAY MEDIA GUIDE
  free service to find and record online radio, Internet TV, podcasts
• AVS VIDEO TOOLS
  convert, split, join, remove commercials, edit, rotate, apply effects, capture, transfer, copy, rip and burn DVD and video files
• EMUSIC
  the best legal music download service
• AUDIBLE
  download audio books, audio magazines, newspapers, radio programs

FairGame will convert the songs you bought on the iTunes Store to an unprotected format (using iTunes default encoder) and keep all the original metadata, lyrics and artwork. FairGame doesn't do lossless DRM stripping. It re-encodes protected AAC files purchased in iTMS into unprotected AAC file using Apple's iMovie software.

It takes 2 min. 42 sec. to convert a 4 min. song to AAC on a MacBook Pro 2.16GHz.

What you MUST DO (only once) to get FairGame to work:

• enable "Access for assistive devices" in the "Universal Access" system preference
• select "Place clip in Movie Timeline" in the "Import" preference of iMovie HD

• select some songs in iTunes
• click on the "Process songs" button
• then don't touch anything and wait until it's done...(FairGame is scripting iMovie's interface to process the songs, don’t interfere)

See also:

• How to remove copy-protection from iTunes AAC files
• Ask your question about FairGame in the DRM removal forum