You can safely skip Fable and go straight for the sequel as there is really no necessary continuity; just the same thing executed another time with better technology and more experience. As for the Knights of the Old Republic games I'm not so sure about the second one, but at least the first one is one of the better roleplaying experiences out there. Once you finish those you should also check out Mass Effect which to me might very well be the game I've enjoyed the most hitherto this generation. You should also get Fallout 3 rather than Oblivion as Oblivion isn't particulary well optimized for the console, and it's really the same thing anyway - just with guns and a less colourful palette.

As for JRPGs you should definently check out Lost Odyssey first as it could safely have gotten away as a part of the Final Fantasy series with Sakaguchi directing, Uematsu music and a more mature tone as opposed to Blue Dragon which I personally found to be quite dull. I mean, on its own terms it functions flawlessly, but there's really nothing remarkable about it. Other than that you should do fine with anything as long as you stay the heck away from Eternal Sonata and its inhumane dungeon designs.

Good luck.