While I personally haven't used an Abit motherboard, my first reaction is one of caution. That said, it looks like a decent board, but here's what I think:
The 10/100 NIC: It's RealTek, not the nVidia one. That steered me away from the Asus nForce board.
The RAID controller: What are you using IDE RAID for? RAID 0 may give you a boost when transferring large A/V type files, but the chance of a dead hard drive goes up quite a bit. Personally, I'd rather invest in SCSI hard drives for the speed and reliability.
Norton Antivirus: This can be had for 5 dollars in the States, but since you're in Brazil, I don't know if you have the same types of deals.
USB 2.0/1.1: While USB 2.0 is a nice speed bump over 1.1, and future proofs the board a bit, how about an IEEE 1394+USB 2.0 card instead?
5.1 DD Audio: It's great. I've got the Boston Acoustics BA7500 speakers, and I think it's on par with my Turtle Beach Santa Cruz. Game sound is bit weird on occasion, but nVidia will probably update the drivers. (MSI has new ones frequently.)
ATA133: ATA 133 seems to me to be a solution to a problem that doesn't exist. Maxtor is currently the only drive manufacturer to have ATA 133 products, and serial ATA is just around the corner. Personally, I'm waiting for serial ATA to buy a new motherboard. (Hopefully it doesn't take *too* long
)
All in all, the nForce chipset is one I would strongly suggest. However, I personally would be more inclined toward the Asus or MSI offerings, and between those two, I'd pick the MSI. I personally don't overclock, and I like the nVidia NIC instead of the RealTek.