5 - 20 minutes
My MBP had a failed videocard from all I could tell. It's just over 5 years old and Apple didn't want to have anything to do with it. They told me at the Genius bar that it is a "legacy product" and parts are no longer available.
I found a good deal on a logic board. I got my thermal past, cleaner and spudget and I went for it.
The instructional guide on ifixit.com was awesome and made the process completely painless. It took a while to do the completed dissassembly slowly and carefully, but after I was done, the MBP booted right up and has been working great for a week. Just follow the instructions and anybody who can handle a delicate screw driver can do this!