Core Duo looks like a pretty impressive chip. Here is a review showing a Core Duo T2400 (1.8 Ghz) slightly outperforms an AMD X2 3800 (1.8 GHz) desktop:
I am a long term AMD share holder and I was impressed enough to buy a Dell Inspiron 6400 Laptop:
15.4" XGA TrueLife T2300 (1.66 GHz Core Duo) 1 GB Ram 80 GB 5400 rpm hard drive ATI X1400 video card 9 cell battery XP home
Currently selling for $1319 canadian ($1160 USD) including shipping. I was unable to find anything comparable in terms of performance and value.
It only has 32bit capability but I tend to think that 2 cores will be more beneficial for my usage than a single core Turion at 64 bits for some time to come.
This Laptop runs very cool, silent and fast with good battery life.