In the comments section, Michael Wolfe raised some important issues about matching funds and electability that have been largely discussed only on political junkie blogs. The concern among many about Clark is that, having taken federal matching funds that limits his campaign spending to about $40 million to the Convention, will be a fish in a barrel for Karl Rove during the dog days of summer if he were to win the nomination. It's a legitimate concern, and it's one consideration that clearly tilts in favor of Dean and now Kerry. But this idea (floated often by Deaniacs) that somehow Rove/Fox News/Right-Wing Media Cabal will turn Clark or Edwards into charred toast seems kinda paranoid.
The money is far less important during the summer months than it is (1) during the primary season, when you're looking to create name recognition and generate momentum to win in a crowded field; (2) the closing two months, when you want to bombard swing states with ad buys and pour money into GOTV operations. During the summer, money is best spent on organization, and there, the DNC can lay the groundwork. The DNC is currently in trouble, but when the dust settles on the nomination, I expect the contributions to pick up dramatically in the summer months. So I think both Clark and Edwards will be okay; I really don't see the money issue being decisive either in the primaries or the general. And if the Iowa results prove anything, it's that process and organizational strength only go so far; an attractive candidate is still more important.
The key is shaping your image for the media. If it's true that the race starts off at a 45-45 split, that remaining ten percent is unlikely to even be paying attention until the debates, if past "swing voter" behavior is any guide. So even if you're sitting on wads of cash in July, that money on TV ads just isn't gonna be that cost-effective. What's more important is in making sure the media's playing a good "meme" about you. As the Dean debacle in Iowa shows, negative media kills. Clark and Edwards, though both vulnerable too different charges, have the best chance of withstanding the media scrutiny due to their superior presentation skills.
And remember, Clark or Edwards would have something just as powerful as "money": they're running full-time for President, and they can show up on TV as often as their advisors think is necessary.
The main problem will be in dealing with under-the-radar attack ads from Rove/RNC, but here's where I think the Internet and connectivity will help: the Clarkie who hears a dirty radio ad in Lima, Ohio can just post the info on the Clark blog, which will then mobilize his activist core to action. This is one area where the internet will make a difference.
Me, I gave money to Clark because as much as I like much of what Dean is doing, I think he's not nearly as appealing a general election candidate and Joe Trippi's "New Voter/Activate the Base" strategy is doomed to failure. (The base will be motivated to throw this bum out of office; "new voters" are a mirage.)