OWC gives you their warranty and offers an extended. But right to bring that up and you do need to consider it. Personally I would take the risk, I have been dealing with OWC for years and they are a great company.
Ryan, you are confusing a graphic card (what drives the computer display) with a video card, that is used for capturing from tape and displaying on an external TV. As for the eSATA here Zane’s comment. You are sending this off to be done, it is not done by apple so you can do it at anytime but you are without the system for a little time. I would definitely not do it for at least a couple of weeks. I would want to give the system a good burn in to make sure everything is working before I sent it off. eSata is something you can add to the 17″ MBP but not the 15″. But since this is your main system you should be adding a monitor to the systems cost so the iMac is a bit cheaper. You cannot edit all day on a 15″ screen