Best performance: 2 cards, one on each PCI-X bus, 2 cards on one PCI-X bus, or a single card with two interfaces?

[<dan-lists.netfilter.org@xxxxxxxxxxxxxx>]

Hello,

I have been sifting the archives to come up with hardware to give me the
best performance.  I read Harald's threads surrounding the performance of
dual Opteron system and am building a box based on those specs (fast memory,
NAPI, 32bit kernel, etc.).  

Here's my question:  

My motherboard has two 133Mhz PCI-X busses.  For best performance should I
(1) put one card on each bus, (2) put two cards on one bus, or (3) use a
single card with two interfaces?

I appreciate the advice.

Best regards,

Dan