I personally think the cpu choice erocker recommended was fine. Though more is always better if you've got the money. Anything would be a vast upgrade from what he has. And actually, the 9600GT isn't a terrible video card. You're in a lot better shape than some of the guys who come to the Warhammer online forum who complain becaue they can't play the game with their 8600GTS coupled with their old pentium D processor
I've got no problem with DFI motherboards so for that price I'd say you can't go wrong. The only thing I have agaist DFI is that they overcomplicate their BIOS. It's great for the techie who wants to adjust everything, but it's hard to understand for the average user. Anyway... that's not a strike against DFI, it's just that sometimes simplicity is good so you don't get confused. Though if you don't overclock it wont' be a problem.
You have an excellent power supply so you can keep that component.
I'm not totally convinced you need to upgade your video card just yet. I think you're better off getting your other componets upgraged first. I'd even say you might want to consider a X38 motherboard instead of the one erocker recommended because at least then you'll be able to buy a second 9600GT and run two cards in SLI. I just don't think it's worth it to jump from the 9600GT to a 9800GT. Yeah, the 9800GT is a better card, but I'm not sure the performance increase justifies the cost of the newer card.