I did not see anything about your motherboard having RAID onboard, so you will need a RAID controller.
is the card that i bought. It is software raid card which means that it isn't the best, but it is MUCH cheaper that way. It has 2 SATA slots and uses PCI-E x1 (which your motherboard has).
1)You will need to download the drivers ahead of time an put them on a USB stick.
2)Install the RAID card with both HD plugged in.
3)When promped on-screen, go the the RAID bios.
4)Choose your RAID setup (in this case 0)
5)Select your main drive and your secondary drive(it doesn't matter)
6)Chose your stripe size. I use 64K (32K and 128K are good as well) I would recommend 32K or 64K.
7)Restart and pop in your Vista DVD
8)When you get to the HD prompt (during vista install), insert USB stick and load drivers
At this point, it will function exactly like 1 HD (with better read/write speeds)
Note: don't update the drivers for the RAID card AFTER you install windows...it caused my computer to BSOD...the most up-to-date drivers at install will be fine!