I'm building a server for the startup I work for, and we plan to initially host it in our office (right next to my desk), and later move it to a data center. In the data center, a small-ish form factor (1U or 2U) is important for keeping costs down, but I'd like it to be reasonably quiet in the office. 2U isn't an absolute requirement, but I'd need a pretty good reason to justify the added hosting costs of a 3U or 4U case.
The server is going to be responding to queries from another server, and running CPU/memory-intensive algorithms to formulate a response, but has minimal storage needs.
Current planned specs (nothing's been purchased yet):
I have an Antec EarthWatts Green EA-430D Green 430W PSU
that's been sitting in a cabinet for about 2 years, but I could also buy a new PSU.
I've built plenty of computers, but never in a server case before. The president of the company also builds computers, and fully appreciates the importance of cooling. I'd appreciate any advice you could offer.