Remember, appointed Senators have a poor track record of winning re-election. That said, since two of the appointed seats are in strong Democratic bastions (IL and NY), the only seat of those three that the Republicans have any real hope is Bennet in Colorado. Illinois is possible if Burris runs for re-election. If he loses in the primaries, Republicans can write that state off.
I don't think it will as bad a year for the Republicans, since the Democrats have more seats up for re-election than they did in 2006 or 2008, but it still won't be a great year by normal Republican standards.
One thing to keep in mind NY, IL & CO all have state Republican parties which are in shambles. Granted the CO Republican Party isn't the complete disaster as IL & NY, and CO isn't nearly as Democratic as those states, but Colorado Republicans tend to like nutters who at this point are totally unelectable statewide.
