Former 4 star general Clark

[MODU]

Clarks own NATO past would hurt him on a head-to-head run against anyone.  It's easy fodder for the anti-Clark machines to use.

[AuH2O]

Generals elected President:

Washington
Grant
Eisenhower

Clark didn't create the US, he didn't win a massive war and also serve time as the Governor of a "military district," and he didn't lead the final push to win the largest war in human history.

Actually, he was fairly bad at inflicting damage on the Serbians, whose military capabilities were essentially unharmed, though embarassingly a US F-117 was shot down.

Enough Clark talk. He's going nowhere, ever, end of story.

[Lincoln Republican]

With Clark as the Dem nominee, I believe the GOP candidate would win by a comfortable margin in 2008.

It would be highly unusual for the electorate to choose someone with no executive or legislative experience as President.  Yes, it has happened before, but it is nonetheless unusual. 

Although Clark is very bright, I do not believe he would inspire the Democratic base, let alone the genuinely undecided, enough to win a pesidential election.