Play on Xbox just wandering if the bugs in dawnguard have a detrimental effect on the vanilla game. Thinking of installing it if not; any thoughts welcome I just do not want to break my game and Xbox.

Haven't experienced that on the 360 here...works great...

Break no... there a good amount of bugs though for sure.

Break? Not completely. I'm hesitant to start a new character though because of the random vamp attacks starting at level 10.

If you really want to play Dawnguard and worried about the vampire attacks just wait to install. Vampire attacks happen at level 10 no matter what the only work around is to uninstall the game when you aren't ready to play that DLC then install it back onto your Xbox if you feel like playing it again with a character. I haven't run into any bugs on the Xbox version myself

No bugs and I really didn't notice the random vampire attacks until I started dawnguard.