GA-7DXR - ATI Radeon & Promise RAID = :-(

Hi
This is my first post so forgive me if I tread on any toes or break some unwritten law's :-)
I'll try to make this short.
Hardware :
GA-7dxr
ATI Radeon 64mb DDR Retail
Athlon 1.4
512mb pc2100 ddr
2 X IBM Deskstar 40gig

The problem I'm having is this.
The PC works like a treat (up & running for 5 weeks now) until I plug ANY hdd into the Promise controller (config as raid or straight IDE) It will not let me put ANY OpSys on they all fail during the formatting section. If I use IDE 1 (with nothing plugged into IRQ 3 or 4) & install I don’t have a problem - the promise controller is detected & accepts the windows drivers happily with no conflict reported. As soon as I Power down and plug a drive into IDE 3 or 4 the OpSys wont boot (W2K Will never boot again !).
My first thought was a faulty Promise controller. BUT if I insert an NVIDIA geforce2 mx the raid works like a dream!?!
Put the ATI & HDD's into a machine with the GA-7ZXR (kind of a non DDR Version of GA-7DXR) and all works fine.
I Have tried manually setting the IRQ's.
I Have tried auto IRQ's (Every thing appears to go onto different IRQ's Anyway!)

I Have tried the ATI/Giga-Byte Tech help e-mail round about with no luck (ATI’s first suggestion was to re-install the drivers - I dont think they read my e-mail very well)

There must be some conflict with The AMD Northbridge - ATI Video card & Promise Controller.

Any suggestions would be greatly appreciated, because I chose this set-up for it’s analogue video editing abilities (amongst other things) and having the raid would be the icing on the cake!

Regards
Matt

I used an Internal modem once....
But it hurt when I walked !