got its hand on a Gigabyte GA-G33M-DS2R motherboard with the Intel G33 chipset and it features a x16 PCI Express slot as well as an open ended x4 slot. What this means is that you can actually run two graphics cards in it.
OCWorkbench figured it was worth having a go and see if the board would work in CrossFire, even though the G33 chipset isn't on the supported list.
They popped a couple of Radeon HD 2600 XT card into the board and got a 25 percent performance increase. Not bad for an unsupported chipset.
You can check out the benchmark figures here
and the full review here