It would be cheaper to purchase an external DVD burner from someplace (lacie is fairly cheap and have firewire ones for Mac booting) unless you need DVD burning while on the move. Last I checked they could be had for ~$120 (depending on FW/USB or both interfaces from Lacie) while the internal Apple one would be ~$150 for labor and ~$200 for the drive itself (if purchased from Apple, either way they wouldn't install a third party one for you anyway).
Although, I don't think the Apple Store would even do it if it's under warranty. Even if you go to a certified Apple service center for this replacement and then later on take it to an Apple Store for some support, if they notice the drive isn't the same as the original it came with (or otherwise not an "Apple" drive) then they most likely won't work on it even if it's a totally unrelated repair.
I say this because I know it works as such for hard drive upgrades under warranty. Even though it can be done by yourself (only on some models), they can claim that whatver third party hardware you put in caused whatever problem you have two years down the road by way of static discharge or some other BS. As for the RAM, sometimes they won't fix it, or will just take it out claiming that is the cause for a problem even if it isn't. That's why they technically have a policy that you must have at least one "Apple" branded stick in your machine (at least that was the policy) to be even accepted for a warranty repair.
