I looked at the ASRock site and it looks to be a good board.
Basically: They are the same exact board on paper. From what I can tell, the only difference is that NVIDIA has certified the ULi chipset on this board, while the DUAL-SATA-2 was made when ULi was still it's own entity (and hence "ULi's" chipset could never be certified, but NVIDIA's 'ULi' could).
If you get a choice, honestly, pick the cheaper one if ya ask me. The components are exactly the same on paper.
EDIT: Aha! there's the difference (just read above comment about sound). Although the sound on the Dual-Sata is not "certified", the drivers still work for my Vista beta 2 install (fixing to check with RC1 version), so get the one that's had the dozens of positive reviews stamped on it--the Dual-SATA-II.
While we are talking about this board...Dual SATAII
I'm using it and an x2 3800 OCed to about 2.7ghz, Geforce 6600GT OCed, Patriot DDR400 Ram OCed, 2 Raid0 Maxtor 200GB, and another IDE 200GB Maxtor for Backups.
Is my Antec TruePower 380W enough juice for OC?
I'm thinking it's not enough juice for all this speed. Temps are fine and well below alarming rates.
The RAIDed maxtors use the +5v rail, so you're fine there. One IDE hdd is ok. What about CD/DVD drives? Any DVDRW drives? Do you ever copy one DVD straight to another? If so--that'll kill you, otherwise, Antec TruePower should have sufficeint power on the +12V rail for your system.
Oh, and this specific antec has almost too much allocated to the +12V and not enough to the +5V, so if you use alot of usb powered devices at the same time--well, DON'T
EDIT: Apparently I'm over-analysing something simple--I somehow missed the overclocking part, despite all of your warnings. No, I'd stay away from overclocking. Honestly, I have more than enough power for that and I stay away from it anyway. I think overclocking is a waste...but that's another discussion, perhaps.