Some people think it’s overkill, but it’s totally worth it to me to have a Mac Pro as my secondary, always on machine. It shares one of my Drobos with the entire house, is still blazingly fast after 2 years, supports upgrades for more disk space/RAID, allows me to have dual 24 inch monitors that match, and not a 24 or 27 inch iMac with a secondary display that is mediocre and doesn’t even line up on my desk. It is my single path into my home network from outside, by which I can control/view my status board, Media PC in the living room, etc… It hosts MySQL for all of my development databases that are shared with my business partner, downloads torrents and shuttles them across the network automatically… and most importantly, it has never, EVER EVER slowed down. I’ve seen a beachball on this thing maybe 4 times, ever. It can actually keep up with me, and that is a computer well worth having.