One thing you may consider and this is my plans. Keep the Apple while it's under warranty factory 1 year and don't buy the extended. Once the year is up toss it on e-bay and get your money out while it's still has a high price tag. That is one thing I'll say is good about Apple's price fixing.. It keeps the prices high, even on used machines.
I'm just about to order the 2.8 refurb. I'll save $200 right off the bat and it has the bigger HD than the new model 2.8. I'll sell it soon as the warranty is up on ebay and I bet I only lose $200 to $300, judging on what prices of older machines go for.
At that point I can either buy a refurb of this brand new generation or pick up what ever the current refresh is.