XFX 8800GT SLI Problem

I have two XFX 8800GT Alpha Dog GPUs. I wanted to try this SLI craze for myself. I was in the middle of building a new PC. the build went great but when plugged in my second Alpha Dog and boot up I get as far as the ASUS Motherboard screen. (basically I can push delete to enter BIOS). XP starts to load but just before login screen one or more of my fans go quiet (I'm guessing its my GPUs shutting down) and there is no display. However, the monitor still registers an input through DVI and Windows is running. I blindly enter my password and I hear the start-up jingle. I have updated nVidia drivers and have adjusted the BIOS to read two PCI-E GPUs. I also have tried both cards individually and they work solo.

So here are my specs:

ASUS M3N72-D SLI Mobo
3.2GHz AMD dual core CPU
3Gb Crucial Ballistx SLI ready RAM
500Gb WD HDD
500W ANTEC Phantom PSU
(2) XFX 8800GT Alpha Dog Edition GPUs
LG DVD-RAM Drive
RAIDMAX Smilodon Case

So could anyone help me out with this?? Feel free to ask me any clarifying questions.

Thanks

L

Lord: That's what I have been thinking. thanks for your input.