Hi, I've been trying to read up on Mac Pro, but there's so much I'm still unsure of. First: Is any 5.1 mac pro identical in basic hardware, i.e. can I reach any configuration by exchanging the CPU daughterboard (if it's a single CPU board), CPU(s) and graphics board (excluding memory and storage)? Are there only one kind of mp5.1 motherboard? I'm looking to replace my late 2006 iMac with something that will last me at least as long. The iMac would still be fine for me if it didn't have the Apple ignored bad solder joints (frequent freezes) that this model suffered from, and if it was upgradeable to new versions of OS X. I've been waiting for a mini update, but then I spotted this ebay ad: http://www.ebay.co.uk/itm/SCRUMPYMA...mputing_Apple_Desktops_CV&hash=item2584abbf78 which seems like a great deal. That's what makes me suspicious About 1600 USD for an entry level 5.1 with a year of warranty and free shipping. Isn't that pretty good or is there a reason for avoiding this model?