I would agree with Reboot. Unless you expect to grow to 40 employees and you are going to run a mail system and a few of the other add ons inside the Xserve, a mini with add on hard drives is much cheaper to expand.

There is no hidden feature in the Xserve which makes things faster. As rb says, the network is the weak link, not what you use as a server.

I have an Xserve but only because I have a rack in a computer center one floor away with a gigabit network back plane in between. Even then I could get the same throughput from any new Mac with a big hard drive or three. The software tools for maintaining it are nice but can be done by simpler or 3rd party means for a few shareware bucks.