The HD4650 is a decent choice for a low-budget card.You can get it for $30 after a mail-in-rebate.Or you can pay the full price and get this card which comes with a lifetime warranty.An HD4670 is the next step up but will cost you at an extra $15-20.There are slightly more powerful cards you can purchase for under $80 but they typically require an extra power connector which your computer may likely not have or simply don't justify their additional cost.
Building a comp for $400 would not be easy, considering the OS is gonna cost $105 at least, unless you want to run linux or get into some shady places.
He could bring over the HDD from his current computer with his current OS.
HDs cost like $30 for a decent one, it really isn't gonna save him much.
It would save him a lot, he wouldn't have to buy a new OS.
Only problem is that he could have XP, which is getting outdated now, and that with a new computer you don't want it to be clogged down with your old stuff from your old HDD.
Windows knows when it is in a new computer, it will deactivate itself, but if he can call them and trick them most people have a lot of success doing that, you can just tell them you bought a new motherboard and they will reactivate it.
Really? That's a bit stupid. It's your OS, your HDD, you should be able to do whatever you want with it.
Well I am not sure if it works with OEM, but if you buy from Dell or Compaq or a similar company they have the computer specs built into it and if you change something the OS knows it. I doubt his current computer has an OEM OS.
-stuff-
You don't happened to be Visedge, the guy that helped me build my computer, do you?