Politics is the art of the possible. You should keep your ideals and work for them, but understand that sometimes you have to settle for second best. So, it depends on the RINO. On occasion, it might be best to vote for a conservative, pro-life Democrat rather than a liberal Republican. But these days, that is getting less and less likely to happen.
Also, you have to consider. Is it worth venting your pique at admittedly bad RINOs like Olympia Snowe, let's say, when the alternative might be to give the Dems a majority in the Senate?
Most of us would have held our breaths and voted for Giuliani if he had stayed in the race against Hillary. He is an extreme pro-abort, which is not something we need more of in the Senate; but the alternative would have been clearly worse.
So, keep your ideals but be sensible. 60% of the pie is better than nothing. And maybe tomorrow you can get a little more pie.