Russert: Were you favor of the war in Vietnam?
President Bush: I supported my government. I did. And would have gone had my unit been called up, by the way.
Russert: But you didn't volunteer or enlist to go.
President Bush: No, I didn't. You're right.
(http://www.msnbc.msn.com/id/4179618/)

And since the wingers brought up Bush's alleged service in the Guard, do you still wonder why he was canned from flight duty? This piece in The Nation might shed some light on that.
"Linke says that Bush's now-deceased commanding officer in the Texas Air National Guard's 111th Fighter Interceptor Squadron, Lieut. Col. Jerry Killian, confided in her and her husband during an encounter at a social gathering as to the reasons Mr. Linke had been brought in to replace Bush. "He said Bush was mucking up his flying very badly and he couldn't fly the plane," Linke said. "Killan told us that he was having trouble landing, and that possibly there was a drinking problem involved in that"--which Linke took to mean a particularly debilitating one, since carousing was almost the norm in such units."