Current plans for build, please critique (~$1300)

This will be my first build. I expect to do moderate gaming, audio/video editing, lots of DVD/CD burning. I will likely OC, but I am not interested in doing SLI at this time.

CPU: Opteron 165 Denmark

Motherboard: ASUS A8N-SLI Premium. This, or the A8N-E, since it has the features I want for less $$, but I understand the A8N-E isn't as good for OCing, and I like the heatpipe. On the other hand, I'm new to OCing and I understand the A8N-SLI isn't easy for novices like myself. Thoughts?

Video card: eVGA Geforce 7800GT 256mb

RAM: OCZ 2 x 1GB 184-Pin DDR SDRAM DDR 400 Dual Channel

PSU: Antec TRUEPOWERII TPII-550

Sound card: Creative Sound Blaster Audigy2 ZS 7.1 Channels

HD: Western Digital Raptor WD360GD 36.7GB 10,000 RPM Serial ATA150

Items I already have that I'm incorporating in this new system:
Case: XION II XON-103 SECC Steel ATX (Black) (ditching included PSU)
HD: WD Caviar SE 250GB 7,200RPM EIDE (WD2500JB) (mainly for media storage)
DVD+RW: NEC IDE/ATAPI Model ND-3540A
Monitor: LG Flatron L1720P

My main questions are, a) the motherboard decision and b) is the PSU sufficient (or even overkill)? However, comments on the overall build or individual items are welcome. Thanks!

After looking into the EPoX board, I believe I'll be going with that one. Thanks again for the advice.