Rackmount server specifications

Hi All,
I was looking into putting together a server meant to be co-located in a
datacenter.
The system is meant to be among other things, a web server, ftp server
database server, and run a data collection program.
It got me to thinking about what the best bang for buck server might be.
I priced some 1u servers, but they all seem to be P4, Xeon and Opteron
systems.
From what I understand, heat is a big issue for 1u servers, especially if
they're stacked on top of each other on a rack.
On top of that, the above mentioned CPUs are relatively hot, making matters
worse.

It's been pretty hard to find out info on Athlon servers, so hopefully I can
get some helpful information here.
AFAIK, all Athlons, including XPs and XP-Ms, and not just the MPs are SMP
capable. Is that not the case?
MPs give an edge in SMP configurations though.

I'm looking at a configuration of:
1u case and ps
2x200GB EIDE HD
CD-ROM
1GB RAM
1u height video card (instead of finding an on-board GPU)
On-board NIC
On-board RAID 1
MB
CPU(s)

Irrespective of the uses I intend above, for web serving purposes, how does
this setup sound?
Is it worth the extra MB and CPU cost to go to SMP to handle a higher count
of user request?
I know that Xeons, P4s and Opterons may give better absolute performance,
but I'm trying to get the best bang/buck

any info appreciated

thanks
Phil