After Mustafar, Vader certainly must have felt in debt to the man who "rescued" him. (Especially since Obi Wan left him to fry!) I doubt he seriously thought about taking his master out again until Luke came along.
Doom will be around so long as someone keeps porting it over to whatever comes along. You can play the original on an Ipod now!
There is another DVD coming out about the same subject. It's becoming a cottage industry!
Those TFN guys may boast about trashing the DVD, but they're still out five bucks, aren't they?