No problem.
I run ObjectDock Plus, with a normal (non-tabbed) dock on top, and a tabbed dock that hides behind taskbar at bottom center.
I have run this set-up for quite some time, and had a motherboard with onboard graphics (64 MB shared), then installed a PCI 128 MB video card by ATI (the motherboard did not have an AGP slot).
There was a noticable slow down in my graphics perfomance with the limited video resources of both the onboard and PCI card when using the normal dock and magification.
I recently swapped out the motherboard for an ASUS with an AGP slot, installed the same CPU and drives, and installed an ATI X700 Pro 256 MB AGP video card.
There is no longer any issue with running a normal dock and my other programs - notably: Photoshop 7, Illustrator 10, Poser 5, Painter IX, Bryce 5.5, and CorelDRAW 12.
The card really makes a difference.