Mandriva used to be the best Linux until KDE 4 came out. The control centre alone was worth it, and it was fast, made Ubuntu look positively pedestrian. I now use ubuntu 9.04, and I'm loath to upgarde to 9.10, as i finally have EVERYTHING working. Ubuntu IS bloated, no matter what they tell you, and is no faster than Win 7.
Ubuntu 64-bit seems more hassle than its worth for the user who just wants to get on the net, email, instant message, playback and encode some medai files, and write the odd document or spread sheet. Last time i used 64 bit Ubuntu, I found the encoding/decoding speeds were not significantly faster, and i never needed the 4 gig ram anyway, so why bother?