Problem with secondary PCI X1 gfxcard

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 I am also very sorry if this post is in the wrong forum, but its called Help & Support so it should be somewhat right at least