Possible Duplicates:
Accepting answer without upvoting?
When you accept an answer should you also vote it up?
If you ask a question and then pick a right answer, should you also up vote that answer? Can a question be "right" but not worth an up vote?
To quote my previous answer
I upvote any answers that are helpful: perhaps they're not the exact solution, but they're alternatives, or on the right path.
Sometimes there are duplicates. If duplicate answers should be 'accepted', I prefer them to be upvoted to match each other, or allow one answerer to retract his answer in favor of the other guy.
But overall, if you're accepting something you're not upvoting, why are you accepting it?
