Thanks for all the feedback!
Would it be nuts for me to consider a refurbished Mac Pro over an iMac? I don't begin to need all the capabilities and expansion potential it offers, but I do like that I can pick and choose my own monitor and easily add memory and expansion cards for things like eSATA ports (something which isn't available on an iMac.) Plus, as Frank pointed out, it would be nice to have the monitor and computer in separate housings so the failure of one doesn't bring down the whole thing.
A refurbished 2.66GHz Quad-Core is available for $2,119, FWIW, and the iMac is pushing $3k the way I configured it.