I have a iMac and a PC, if I start them both at the same time, I can have read my mail and be online with the iMac, before the PC is booted up.
My iMac is coming up to 3 years old, (bought the extended warranty and never had to use it) I've never had a problem, it's never locked up, it does what it says on the box... end of story.
I'll be selling this one soon to get me the new 27" LED iMac
Whats specs on your mac and how much are you selling it for?