My first PC was a 350MHz Pentium II. When I felt the need for more speed I went for the AMD Duron 650 as it seemed to offer the best price/performance on my budget. That was later upgraded to a Duron 1200 that remains my fastest home CPU. Some people still prefer Intel over AMD due to AMDs issues in the past with compatability and lack of performance, but they have come a long way and now seem to be neck and neck with Intel. I aspire to one of their 64 bit chips. Dual-core would be even nicer and would handle my prospective video processing with ease. It will have to wait until I get budget approval.

Modern high-end PCs use a lot of power, so the energy efficiency may be important to those who leave their PC on all day. Tom's Hardware have done some testing on this and it seems that the AMD PCs are much more efficient that the Intel ones. Under full load this can be around 150W as opposed to 250W. Over a year that amounts to a lot of money.

Of course, if you really want to save energy then go for something like the Mini-ITX that will draw a fraction of that power, but is probably not aimed at the power user. I would go for one of these as a 24/7 media PC or file server.