What kind of hardware do you use for production servers? IE... RAID, how much RAM, processor(s) etc... If you use RAID, what kind of RAID setup do you use? Is everything hot swappable?

In an office I recently saw a hard drive fail on a server. I grabbed another drive, popped out the bad drive (while the server was still working in production), put the new drive in and off things went. It took an hour or so to rebuild the drive and the users experienced zero down time.

We actually have a mix of Dual Xeons, P4s and Celerons. Our Xeons handle clients that need more horse power while the Celerons obviously handle the lower consumption users