Problem with secondary PCI X1 gfxcard

[jajajanse]

My system is this:
Motherboard: Abit AB9
CPU: Intel C2D E6600
Memory: Corsair TWIN2X 6400C4
Primary display adapter: XFX GeForce 7600GT (PCI-Ex16)
Secondary display adapter: HIS Radeon X1300 HyperMemory (PCI-Ex1)
OS: Windows XP Pro SP2

My situation is this:
I have two LCD monitors for desktop, and I also have a TV and a projector connected to my computer via VGA cables. I therefor need two display adapters. I use the primary adapter for my LCD monitors, and I use the secondary for the TV and the projector.

My problem is this:
When I play any videofile on the TV or the projector (or whatever else is connected to my secondary display adapter), it works fine. BUT - when I try to play it in fullscreen, it gets all "pixely", and the CPU for VLC goes to 45-55%. As a result, the video is unwatchable and my PC is working extremely slow.

I really hope someone can help me out with this problem. If i explained something badly or did not include enough information, let me know

 

[mpjesse]

does the problem occur with ALL video files and in WMP?

 

[jajajanse]

does the problem occur with ALL video files and in WMP?

I have only tried different variations of AVI files so far, but the problem occurs in every one.

I have tried VLC, Media Player Classic and the very newest version of Windows Media Player. Same problem with every one.

I have really no idea about this stuff, but it kind of looks to me like the secondary display adapter is telling the CPU to take care of the stuff its supposed to take care of itself (playing videofiles). Which in return results in a very poor quality. Just a thought though...