After having the Neo 4 Platinum, I have to say it is a great board, possibly the best board I’ve ever had (my first build was a 386DX-20 in 1994 which should give an idea of how many I’ve had). Full featured, stable, and performs well.
You can choose the boot order in the BIOS, so if you want to choose which SATA drive you want to boot from, that’s definitely an option. There are a couple of changes I’d make in your build, though.
I wouldn’t choose a Rosewill power supply. There is no way to tell who made it, and they’re a rebrander. Spend more money on a brand-name power supply such as an Enermax, or the Fortron Blue Storm. You will be happier in the long run. Power supplies aren’t glamorous, but choosing the wrong one can result in system instability and wierd quirky issues, and choosing an average one means you’ll need to upgrade the next time you rebuild to a beefier system. Don’t rely on watts alone; a lot of cheaper manufacturers specs range from misleading to outright lies; buying a brand name PSU will help you avoid this. Amperage is important; make sure you have a PSU with at least 20 amps on the 12V rail, or a dual 12v-rail PSU with at least 15 amps on each rail.
For hard disks, Seagates also have five-year warranties. Raptors are fast, but they’re noisier than other drives and run hotter, and cost a lot more. For that kind of money, you can get larger capacity Seagate 7200.8 SATA2 drives which are fast, quiet, and run cooler, and also have Native Command Queuing that the Raptors don’t have. Unless you’re going for server performance, I don’t see the need for Raptors.
Another user recommended downgrading the CPU to upgrade the video card. If you’re going to game, this is wise advice. An ATI X800XL will cost you a bit more; save money by dropping to an Athlon 64 3500+ or so. Spending big bucks for the fastest CPU isn’t the best idea. Like someone else said, I’d also change the DVD-RW drive from LiteOn, I’d probably go with NEC or Pioneer. LiteOn burns CD’s great, but has a hit-and-miss record with burning DVD’s (though their DVD-ROM drives work pretty well).
If sound is important to you, get an aftermarket sound card and disable the onboard sound. Very few boards have good onboard sound these days, even if they’re good boards. An OEM SoundBlaster Audigy 2 ZS can be found for around $50 on Ebay and is worth considering.
Finally, your fan setup is going to make for one heck of a noisy case. It’s far better to replace 4 80mm fans with one 120mm, which is quieter and delivers plenty of air. Look for a quality case that takes two or three 120mm fans, then go with low or medium noise fans such as Panaflo or Vantec Stealth. You’ll be a lot happier.