I have the A7M266 with a Athlon 1.33, and the ATI AIW.
I put in the promise FastTrak 100 PCI ata 1000 RAid controller with 2x IBM 75GXP 30 GB drives ( they dont even heat up they are so good ).
This combo is lighting fast! And I get to have 2x extra ata 100 controllers, which I just could not survive without.
On board RAID controllers usually give you way more hassles than an external PCI Controller.
Plus its available now, no waiting for up and comming Mobos, I mean I waited long enough for AMD761 boards,
My 2 cents worth,
Cheers