Concerning the extended/mirror desktop function of the imac, is it useful? I already have a lcd monitor, and I like the idea of using two monitors at once but I think it is more for the geek cred than functionality. 24" is out of the budget. I'm still in the planning stage, but I'm thining 17" imac to pair with my 17" lcd. Do a lot of you use this feature? ...mostly interested in the extended desktop not the mirroring. If so can you provide a brief description of what you use it for or why you find it useless. Thanks.