I'm not even going to get into why people are recommending bloody 7800 cards for an email/internet PC
Build him a nice machine for $900, invest the majority of your money into CPU horsepower...pocket $100 for service charges and then give the other $9000 to charity
Just because you have the money doesn't mean you have to spend it...I'm a hardware consultant, I sit down with people and figure out what people want their computer to do, I assemble them a rough outline of what they need to do what they want and then hand them a quote...this is no different, you know what the guy wants, now build something appropriate, not some whacked out bragging rights dream machine