I'm about to install my own colo server in a data center. I need to supply the hardware myself, and am free to pick any components that suit me as long as it fits in a rack (I assume a 1U form factor).
Rob, I'd be interested to know your reason for going for colo rather than just renting a dedicated server (or a few).
This will be for use mostly as a LAMP web server running content management systems; most sites will have low volume although a few are fairly high. Other than the LAMP sites, I do run a few moderate volume mailman mailing lists. I have a low budget and want to get the most bang for my buck.
Off the top of my head - the Sun V20z with dual Opterons is cool, IMHO - but see below.
AMD Opterons may be a better value. HP has an Opteron package (DL145) that's inexpensive with base RAM, but another gig of RAM is $1K. I've seen better deals, but the service and support HP offers is attractive. FWIW, I will have easy physical access to the server in the data center.
I think it will be difficult giving you any sound advice without knowing the load on the box, the expected reliability, availability etc.
I'd like to hear what the consensus is on the various elements of server selection; importance of various components, brand name vs. generic, Intel vs. AMD, ATA vs. SCSI, value of extended warranties, etc.
My favourite setup is something along these lines: Dual server in Linux-HA. Both with mirrored IDE disks, unless the server will have lots of concurrent traffic, in which case I use SCSI. CPU and RAM will depend on the purpose, but always single CPU (dual CPU boards are less cost-effective, unless you're short on space), and 512-1024Mb RAM unless it's a database server where I'd probably opt for as much RAM as possible. Two NICs per node, each connected to a separate switch/network. I used mirrored disks in each node as the drives tend to be the first to go these days. /Per Jessen, Zürich -- http://www.spamchek.com/freetrial - getting rid of spam and virus - once and for all!