ive youve got time you should wait for x48 mobos which are just round the corner, the Asus P5E3 Premium looks like it might be a winner if you want a powerhouse, but then again its pricey and so is ddr3 ram ;p
I know the Asus ROG version is the Rampage. I'm torn between getting that or a Striker II Formula myself. I already have an Nvidia card, not keen on the idea of going back to ATI (at least at this time). But early tests seem to indicate the X48 is a better chipset than the 780i.
Mind you, I'm waiting for the Q9450 to come out, and who knows what BIOS bugs will be worked out in the meanwhile? I'm content to wait for now...
I've also been considering getting the 790i if DDR3 prices drop a bit by the time it comes out. I think when it does come out, ddr3 prices will drop due to nvidia and intel then having ddr3 capable boards. From what I've heard its been slightly delayed as nvidia didn't want to release it so soon after the 780i but I think its on course for somewhere in march, I'm guessing just after the 9800gx2.
As for 780i vs striker 2 formula. I have an nvidia chipset simply because i prefer them and I like to have the option to run SLI if I want to. If you don't plan on running SLI then the striker 2 formula is an excellent board but the customer support, warranty and step up programs at Evga are fantastic. If I was in your position, it would come down to SLI for me. Also remember than the 780i is only marginally different from the 680i.