I have an ASUS M2R32-MVP motherboard with AMD 64 X2 cpu. I want to ultimately have as the boot drive a raid array with mirrored 250 gig sata drives. How? Please read my whole post before responding.
When I am booting from CD with XP and the 250 gig sata drives are configured as raid, XP doesn't recognize the drive. When the drives are not configured as raid, XP only recognizes 139 gigs for each drive.
There is a point when XP boots from the CD when it asks if I need to install 3rd party HDD drivers. When I say yes, it later asks for the drivers on a floppy drive. I don't have a floppy drive.
I have temporarily installed XP on a small EIDE drive as the boot drive. With the motherboard-supplied raid drivers loaded XP recognizes the raid drives fine.
I can think of two possible solutions which I haven't tried:
1- I have read where someone imaged the boot drive to the raid drive. Does this really work? Must I purchase imaging software?
2- Would a USB floppy drive (and with raid drivers copied to a floppy) allow me to boot XP from the CD and directly install XP to the raid drive? Must I purchase USB floppy?
Any advice would be appreciated!

Answers to your questions:
1 - Yes, but your imaging software might not recognize drives that require 3rd party drivers. If you could boot windows from your single drive and then set up your raid from windows you could image your boot drive to a secondary drive then image it back to the raid. But if you use a product like Acronis which will work without windows (it has it's own built in OS which boots from CD) it will probably not recognize the raid..

2 - Yes, this is probably your best choice. Just boot from CD, load 3rd party drivers during windows setup from USB floppy and setup windows from scratch.

I personally have done what you describe in question 2. I recently setup two Server 2003 boxes using a USB floppy to load the drivers, works like a champ.