Voting Democrat in a Red State?

[tdjustin3000]

I live in beautiful state of Tennessee, quite a strong red state. (We didn't even pick Gore in 2000, and he *lives* here). To add to my "redness", I am registered to vote in Williamson County, one of the wealthiest, whitest, Republican places around (In 2004, residents of Williamson donated $144,000 to Bush, $34,000 to Kerry)

I'm not particually sold on any prime candidate as of yet, but I suppose I'm leaning towards Obama. So here's my question:

Should I bother voting?
If I want McCain to win my county, I don't need to do anything. That will be taken care of.
If I want Obama or Hillary to win, in reality, my vote will do nothing to help.

So what motivation do I have to vote? I know it's my "American Right", but in my situation, I'm not sure if would make the smallest difference. Does a certain percent of votes (even if you lose) help a canidate in anyway?