Server Spec for MailScanner

[Pete]

I think i have successfully lobbied for a 'new' replacement server for
MailScanner at work.
we originally installed to prove it would work and re used ancient
hardware we had lying around, 2xp200 NEC server, the newer releases of
MS have meant this machine not longer cuts it, even for our 3k messages
for day.

So, we buy second had compaq proliant servers from a local vendor, with
original 3 yr compaq onsite warranty.

Additionally i am lobbying to re route our new parent companies mail via
our mail scanner, so our volume may double/triple. they currently have
NO protection, just 2 exchange 2000 servers in the DMZ with NAV,
needless to say they have many days of no email at all.

For 6k - 9k emails per day, running Clamav and etrust would something
like a Proliant ML370 2 x P3 800/1GB RAM and scsi HDD running either
suse or red hat 9 (my FreeBSd skills are not sufficient for this yet) be
enough horsepower? Alternately our vendor has a single Ml310 P2.8 /1GB
Ram and scsi. will mailScanner benefit more from dual CPU or faster CPU
considering the load i described above? Or would I be better off spend
more on RAM? 1 GB seems like plenty of RAM to me, but then again i
havent processed 9k emails before, and some of you have, so hopefully
some one could advised on which hardware will benefit MS more?

Additionally we may have access to an additional scanner license - would
i be better off running 3 x virus scanners, clam, etrust and
sophos/f-prot, or just run 2, clam and sophos/f-prot, especially
considering my hardware limitations?

Is there a massive difference in hardware requirement between processing
6k or 9k emails per day?

thanks in advance to anyone who can offer suggestions