HW Recommendations

[Kit Halsted <kit_(_at_)_kithalsted_(_dot_)_com>]

Ever so slowly, the colo project I'm handling for my boss is coming 
together. The latest requirement was 2 boxes, a 1U bridging firewall 
& a 2U backup box, but I'm thinking I can get better cooling and 
bang:buck by combining these into a single box in one of the new 
Antec 3U cases. I'm also thinking of going with an Athlon CPU for 
price/performance reasons, but this is where I need some advice. I'm 
still pretty much a newbie in i386 hardware-land, & I'm seeking input 
on what mobo/processor combos will work well with my other hardware & 
software. Here's what I'll be using:

Hardware:

i8255x (fxp) NICs (3 of 'em, 1 with an IP & 2 solely for the fw 
bridge) (Does Intel make a 2- or 4-port version of these?)

Video Card (No X11, I'm thinking a cheap AGP card just to keep it off 
the PCI bus)

U160 SCSI card. I'm thinking Adaptec 29160, unless anyone has a 
better suggestion.

18GB Seagate U160 (or U2W if I can still find one) boot disk

Ecrix VXA-1 U2W SCSI tape drive

EIDE CD-ROM, whatever works.

Floppy

Software:

OpenBSD 2.8 (or 2.9 if the schedule keeps slipping like this), -stable

IPFilter

Amanda

Any help understanding what differences between the various mobo 
types will actually translate into something OpenBSD can use would be 
greatly appreciated.

Thanks,
-Kit