Serial ATA is faster, however, harddrives do not support it yet, in fact, most drives still are only ATA100. Maxtor has only the ATA133 support.
As for ASUS vs. Gigabyte, well, it's a mixed bag really. I had always had ASUS boards until I got the A7V-333. That thing was horrible. I couldn't even boot Windows with the slowest timings (100 fsb, crappy memory timings). I had to ship the thing back. My current Gigabyte is awesome, stable (rock solid). It's never crashed once, and it's been running for a while now. Both are awesome brands, and both have had crappy boards as well. I read one ASUS board was having problems, but I can't remember which one!
I had many different boards before, ASUS, Shuttle, but, nothing like a Gigabyte board. This is my first one, and I love it. BIOS update features are awsome. It's an AWSOME board.
I would reccomend getting anything Gigabyte, especially
My first MotherBoard i had was a Ga-7VRXP
It didn't work right out of teh box, I was installing Windows XP, and teh VGA slot went :OOF::
I sent it back and they sent me a new on, it sits in its box in my attic, I bought a ASUS AV7333, and I have had no problems with it.
I would recomend going to MotherBoards.org, they rate teh newest mother boards...