WinXP 64bit has access to 4 more registers; theoretically, it can do things faster than Win32. However, most programs hardly need 64bit addressing (who has more than 4GB of RAM? servers, mostly) and most encoding apps, which CAN benefit, are written for 32bit Windows. Even the 64bit Linux distros don't take advantage of 64bit processing (ie, SuSE 9.3, etc, as of 2005-05-23) For the record, my Athlon64 3000 is rock-solid, not a single blue screen since inception. Uptime is months already.