I'm running a puny AMD 1800 Ghz since about two years.
It's actually pretty good in comparison to the 750Mhz AMD I had before and
the diverse collection of Intels and AMD's (mostly because of price) I had
throughout the years.
I'm running WinXP and Suse on it. I combined it with a 128 Mb ATI card
and 1Gb of RAM.
Shogun and M:TW run perfectly.
Rome is slightly laggy but SP is very playable. The only thing that really
bothers me is video editing and conversion. It takes forever.