Balancing Idealism and Cynicism

I'm a political junkie, and I'm always trying to balance somewhere between idealism and cynicism. It's a challenge that I face every election cycle. I know I'm not alone as I look around the blogs, where some believe in their candidate, while others believe that the system is rigged and the corporate oligarchs control our choices.
Both are true.
As an idealist, I work every election to insure that (at least in my locale) all the votes are accurately counted, and that all eligible voters get to vote. Zymurgian chides me for "believing in the system", and in a way I do. Our political system is seriously flawed, but it functions adequately if enough people get involved.
On the cynical side, the corporate media has tight control of the messages, and the voters are left to choose between media approved candidates. Can't upset the status quo.
Over the years, I've worked on dozens of campaigns, and most have lost. I'm at it again this campaign season, ever optimistic. In the end, I usually end up voting for the "lesser of two evils", like most voters. It's a sad, frustrating reality (I admit that I'm much more liberal than the general public). The Democrats repeatedly disappoint me, but the Republicans are even worse.
Is our political system broken? I struggle with this question. Compared to political systems throughout history, ours works pretty well overall. But it seems to be failing most of us, "the people." I'd love to see a true "populist" party that worked for "the people", but the vast majority of "the people" don't seem to care enough to get involved. Can't say I blame them; politics in this era is a nasty, brutish, slimy process without instant gratification. "American Idol" is more entertaining and less time consuming.
Despite my mixed feelings, I keep re-entering the fray. I keep telling myself "if I don't do it, who will?", but that may just be the rationalization of an addict. I do believe that we'll end up doing the right thing, after exhausting all other options.