Advice needed before making the switch

Greetings all,

I'm a pc user and have been wanting to make the switch for a long time now.
This seems to be the right time to switch for obvious reasons. My delima is this; I'm not sure which iMac to get. The 21.5" with 3.33ghz & 8 gb ram with 256 video card or go big with the 27" core i5 or i7. I do a lot of cad work - Autocad 2009, sometimes Revit and i would like to do more (better) photo editing & start doing video. Can anyone point me in the right direction based on experience? I'm willing to go big to avoid having to upgrade every year or two. BTW, I live outside the US so purchasing might be another issue regarding discounts & rebates.
Thanks in advance

I think either machine would satisfy your needs as far as performance is concerned. You'd know better, but it seems to me that the larger monitor would be nice for CAD work. Do you use multiple windows at the same time? If so, the larger work area of the 27" would be an advantage.

I often multi-task in various programs or have several drawings open at a time. I did a fair amount of research & looked at benchmark scores and the i7 is very impressive. However, there's no results for the i5 with 8gb of ram. Either way, the old saying sounds about right, "buy the fastest you can afford now"

Go with the quad. It seems as if you are going to use a lot of intensive programs for design!

I didn't think AutoCad and Revit would run on a Mac. I know that ArchiCad will, but that's BIM only (like Revit).