But make sure you dont have any important data on the RAID drives as they have higher failure rate than single config drives...
So I would say - 3x Samsung F3 for about $150 -
2x in RAID 0
1x For data backup
The problem with motherboard RAID implementations is that if you change motherboards, you cannot just move the disks over to the new motherboard. You need to have backups and rebuild the array. With a relatively small array, that's not much of a problem.
On another thread, a poster wrote in about the problems of moving two 2 TB arrays to a new motherboard. That's why I pretty much decided against using RAID.
@jsc - Yes it is very difficult to move RAID drives from one mobo to another...
It would only be successful if both the boards(Current one and the mobo that you are changing to) have the same RAID controllers...
Whether or not RAID will benefit you is dependant on what you do, and where you are looking for a speed increase. If you move around a lot of large files, if you would like your PC to boot 3 seconds faster, and some programs to load 2 seconds faster, then RAID may be for you. Be sure you run a good backup. Be sure to run a good backup. Oh, and be sure to run a good backup. You also will actually suffer a slight overall hit in performance as latencies on a RAID setup are longer than on a single fast drive, but it is not a big noticable amount. Also, be sure to run a good backup.
If you are a normal user who stores pictures, plays an occasional game, loads up your MP3 player, and checks email, maybe a little Photoshop or other application, you do not need RAID. Period.