5870 ATI driver refusing to detect card

Hello,

I am using a DIY Vidock (external graphics card) with a radeon HD 5870. Everything works; the computer detects the card and everything, but the one problem is that the Catalyst drivers do not. No matter how many times I install different drivers, it never detects it. When the onboard 8400M GS is on, it says that the driver is not compatable with the current enabled graphics adapter. When I disable the 8400M GS, it says that "no ati driver is installed, or it has malfunctioned" (something along those lines). The 5870 shows up under "unspecified" on the device manager.

What am I doing wrong?


My specs:

Laptop = Dell XPS M1330
4GB RAM
Nvidia GeForce 8400M GS
Intel Core 2 Duo T5750 (2.00 GHZ)

DIY Vidock =
ATI Radeon HD 5870
480W PSU
PE4H 2.0
EC2C


OS = Windows 7 Ultimate 32-bit

Thanks!