PCIe Expanders

[clasicunlock]

I'm thinking about expanding my rig to include multi GPUs and I'm looking for some advice from those that have set some up previously. I'm looking for the best value for money and speed, I don't want to spend too much so hoping I can add some kind of expansion to my current setup which is pretty crap but it works. My problem is I have an old motherboard with only 1 PCIe slot and a Geforce 9800 GTX +.

What I'm thinking of at the moment is switching to AMD and getting a couple of 5970's, then maybe adding to it as and when I can. So what I'm wondering is what kind of performance hit will I take from this kind of setup, and is it better just to buy a new motherboard? In other words will it just bottleneck?

I was looking at the nestor PCIe expansion block or something similar:
http://www.netstor.com.tw/_03/03_02.php?OTM

What does everyone else use for the multi GPU setups?

what you are showing here is expensive 1500$ minimum this expansion wich i dont see it very good.

www.magma.com they got also same thing pci-e expansion with 16 pci-e

but is very expensive and with that money you can buy 10 x 5970 GPU and get an inexpensive motherboards and processors and old 40gb hard disks.
That boxes are for Video Rendering wich is not used all the time 99% like brutefoce wich needs fresh air.

you can buy pci-e cable extender and have 2 3 pc`s is best thing.