check this out:
http://www.infinitemac.com/f5/succes...-leopard-t956/
OnBoard "fake" RAID may give you problems. I did some research but came up dry on getting it to work. If you are wanting to install your OS on a RAID array Id say an actual hardware RAID controller would be your best bet. A true RAID controller, one that does all the processing onboard and doesn't pass it off on your processor (oh and one that you can find OSX support for).
I also saw a few post where someone managed to install on a software RAID created, I think, using Disk Utility from the Install disk before actually installing.
It is probably a bit easier to do an install on one of your two drives and use the second one as a backup for the first. Then if you have an issue you can restore a working OS. Id wait till you find out how to get your machine running smooth before Id opt for installing on a RAID array.
[EDIT]
Memory:
4GB of memory may cause some issues. Im using a fix for this problem but I don't have the same chipset so you might be better off using the boot-flag
When you startup you are given the option to add boot options. You can replace the 3074 with the amount of memory in MB that you want OSX to see. This limits you to 3GB and so should eliminate any issues that may occur.
Backing up your install:
1. boot your install disk.
2. Select Disk Utility
3. Unmount the drive you installed on
4. Got to File/New/Disk image from folder and select the disk you just unmounted
5. Save to your second drive and reboot.
Now you have a backup image you can restore from if you bork your system. In addition you can mount this image and pull old file from it if needed.
P.S. Im a fan of 10,000rpm drives. They are def nice.