I'm using the Asus P5K Deluxe, but they have new ones out based on the P35 chipset like the Blitz and Formula...I have Crucial Ballistix 8500 RAM, I like it but theres other good stuff around like Team Group or High end Corsair. As long as the RAM is Micron they all perform quite well.
If you want an ATI card you can't really go past the HD2900XT I don't own one but if I was going to upgrade I'd go that way, The P35 intel chipset supports ATI crossfire too.
The X38 is still a couple of months away from hitting retail I suspect, but until I see some benchmark results for it I'm not gonna get too excited.
Cool Case owns 2 ATI 2900XT's.. he might chime in here soon, he might even sell you one lol..