I've been looking around and I'm yet to find an x86 machine with more than 2 66mhz 64bit PCI slots.

Does anybody know of such a machine (with 4 or more 66mhz 64bit PCI slots) they can be on separate PCI buses.

I don't think there are any. The best I know of is the Intel Quad Coppermine board used in their Koa (SRKA4) platform. Penguin sells that machine as the Relion 4500. VA used to sell it as the 4450. I'm sure you can still find someone offering it. The Intel STL2 and all of the other boards built around the ServerWorks chipset appear to only support 2 fast-wide slots. ccb