I want to order a 2.4ghz Penyrn and customize it with a 250gb harddrive instead of the 200gb it comes with. The one thing i'm worried about is the Apple exchange policy on custom built orders. I know they don't accept returns, but what about an exchange if I get a yellow screen? Should I just go with the stock 200gb drive to be safe so I can exchange it in store? Even if they do let my exchange a CTO i'll have to send it in the mail and wait for a new one right? Will they let me exchange for another model if the CTO has a yellow screen? Or will they just replace the screen? Does Apple even see this as a problem that they will replace? Thanks.