Thinking about getting a used Mac Pro (duel quad-core) in about a year. Looking at current pricing used Mac's, it doesn't look like the pice really goes down much. I've not even seen a used Mac Pro with a single quad core for less than 75% of retail, and at that price I might as well buy one new, customized to my liking and with the AppleCare protection plan. I was hoping that the new Nehalem chips would drive the price down of the used ones. Do used Mac's just hold their value indefinitely? Or am I just not looking hard enough?