The main question can be answered in a few lines, Can Linux replace Windows?
// That all depends on what you do. If you use mainly office and graphics applications and the net then Linux is a dead winner. If you want to play the latest games then Linux is no good as even Wine (Windows Emulator) doesnt work all that well (Fast).
What i have done is used a dual boot, Linix for business and most other tasks, Windows for Games (FS2004). I browse the net on both but find Windows easyer when using those P2P applications and Wi-Fi.
Mandrake Linux or Suse i have found to be the most switch friendly and then i have moved on to RedHat. Lindows or Linspire is supposed to be the closest Linix to Windows and claims to run most Windows applications, i have not a copy so i cant vouch for that...