ZDNet has a review of Windows XP Pr x64 Edition RC1. good review with some interesting info. they do some benchmarks too. The only reason i havent even though about upgrading to 64bit (well, i have though about it, but never actually got the upgrade process moving) is the price of the Opteron. The Athlon 64 is nice and all, but after going SMP, you cant go back! the opteron ranges in price from 480EUR for the 2Gz Opteron 246 to a staggering 870EUR for the 2.4Gz Opteron 250. and thats only for one and i would have to get a board and ram too! i was going to get an estimated price of a nice machine (2 Opteron 250s, 4Gb DDR ram, main board and 2 400Gb hdds) but Overclockers.co.uk dont have any opteron boards…