I don't see how the Senate can stop Roland Burris from taking his seat as Senator from Illinois. Actually unless there is some screwed up rule giving the Senate veto power over sitting a Senator that has been appointed by a seated Governor in compliance with his legal obligations under that States Constitution, I don't see how they can stop it.
In fact they would be much better off seating him quickly and letting the issue go away. If the Dems don't think he is the best person for that job then just run another candidate in the 2010 primary. Which is what a year from now?