I've recently built a very similar system:
Phenom II X4 955BE
2x2GB Crucial Ballistix DDR3
ASUS 890GTD USB 3.0 SATA 3.0 Mobo
Cooler master silent pro M600 600W PSU
Lian Li PC-7 Case
All in all I'm pretty happy with it. The ASUS has quite good fan control built into the BIOS (if you can get it working properly) so although I was planning on getting a new cooler, that's been put on the back burner as I can barely heard the one I have!
Like you I bought an 890gx board so it can handle 3D but can also upgrade to a decent gfx card when the funds allow it!
The ATI HD4290 onboard graphics is fine for all the HD video and full screen flash you can throw at it and it gets 4.6 in Windows 7 Experience for Gaming Graphics if you were wondering (easily the lowest score on my system though)
Let me know what the cooler you decide on is like!