Which gaming computer would be best?

The first one is far better. If they are the same price then there is no reason to go with the 2nd. The 9800GT is really just a repackaged 8800GT and 2 of them will go much further than one. The CPU in the first is enough to be able to notice an improvement. The 4GB will only show as 3.5 if you are in a 32bit OS although 3.5GB is better than 2GB. The hard drive is bigger in the second one. But they run so cheap nowadays that when you need more space spend ~ $60 and you will have a 500GB