Thanks for all of the replies guys!
The following benchmarks caught my eye as I was hunting around for more info on this:http://www.anandtech.com/cpuchipsets/showdoc.aspx?i=3153&p=9
Clock for clock, it seems like the Phenom doesn't do too badly in games.
I suppose I'll tell my friend to try overclocking (I know Phenoms are notoriously bad), and then recommend he grab a 4870 when they're out.
@Moe - As Houston said, he's got the RAM in a 2 X 1GB - 2 X 512MB config, so it's working in dual channel mode.