multi monitor support for 4 monitors?

[Hampel]

Are there any graphics cards beside the ones from matrox that support 4 monitors and have useable OpenGL drivers available? The OpenGL drivers from matrox seems to be very buggy (following some threads in the OpenGL.org-forums). We definitily need the features VBO, pbuffer, and S3 texture compression (S3TC)...

Any suggestions?

[def]

The Quadro FX600 PCI gives you two additional screens via PCI slot. But I don't have any experiences in setting something like this up, but I know the monitor setup under windows can get tricky.
An SLI mainboard is supposed to do 4 screens too... (with 2 PCIe cards)