I've never had an asus board but they have a good reputation.

If no overclocking, are you going to run crossfire? have you picked out ram? 4gb should be your minimum since ddr2 is dirt cheap.

my last 3 boards have been gigabyte and despite my current boards quirks ( weird ddr3 ram voltage issues ) i'm going to stick w\ them.

as far as cases, maybe you can get a good deal on a 900 ? they had them for $50 a while ago @ frys but idk. i got my 3d aurora off craigslist for $50 and it was still in its box w\ plastic ( yes.. im notoriously cheap and thrifty )
I like the cosmos but its a huge case.