Stay away from official 2.2. It is not as fast, or even as stable as most of the current 2.2 ROMs available. Plus if you decide to root, it will be that much harder to do. Trust me when I say stay away. If you like touchwiz, try bionix V 1.(whatever they are up to now) touchwiz edition. On top of the current 2.2 ROMs out there being fast and stable(and much better than samsungs bloated release) there are now 2.2.1 ROMs surfacing that are 95% reliable. Give it a couple weeks and they will most likely be ready for daily driving. Or if you are feeling extra brave and want to run 2.3.3, CM7 has been released for Vibrant. It is still kind of buggy, but again... a couple weeks and I am sure it will be daily drivable. If you still decide to run stock 2.2 via Kies, still keep your eye on the community as I see a lot of very interesting things happening in the near future.