(to skip the details, jump to last paragraph)
A few months ago I built what I thought was a beefed up box with an AMD Phenom II X4 955, 8 GB DDR3 1333 mHz RAM plus a nice motherboard (can't remember exact specs). However I couldn't get a VirtualBox Windows XP guest machine to perform well in it, and later read that AMD CPUs don't work so well in general (???).
Anyway, I have been asked to configure and buy a new notebook for a family member, who needs to run a few legacy Windows apps but really wants to use Ubuntu as the main OS to try to squeeze good multimedia performance out of it. Right now I am looking at AVADirect Clevo W860CU with NVIDIA® GeForce® GTX 460M, 8 GB DDR3 1333mHz RAM, and a 7200-rpm hard drive.
Due to past experience, I am not confident about virtualisation. One question is: Would a quad core i7 (say 840QM) with slower clockspeed perform better (or worse) than a dual core i7 (say 620M) with higher clockspeed for virtualised guests under Linux? Or should I just tell the person to go with a different host OS?