Hi guys, I'm planning an iMac purchase and just want to ensure I'm getting the right model. I use Motion quite a bit on the 21" model so I'm thinking of going for the 27" model this time as the interface in Motion is pretty hefty. Using motion means I'm dealing with HD video, though not too much of it. I'd also like to be able to play some games on Steam via Windows on ocasion, though that's not my primary concern. I'm thinking the base level 27" iMac should be fine, but I'm looking at the next step up, and it's upgrade options, and wondering just how much of a difference it makes? An extra 0.3ghz on the processor doesn't sound like much of a difference? I'm not expert at hardware though. So if you were in my position, which iMac would you buy? And based on the needs I listed above, would you go the extra mile and upgrade anything like graphics memory or processor? Thanks for any input!