BFH, in the US it's actually much better if you have previous flying experience. Do a little research on it on the AF sites and visit <a href="http://www.studentpilot.net" target="_blank">www.studentpilot.net</a> which is a US message board. There's a military flying section which has a whole range of military pilots who can answer any question.
Back to the flying hours....your flying hours are actually incorporated into a calculation which is your PCSM (Pilot Candidate Selection and I can't remember what the M stands for). The greater your number of hours, the higher your PCSM is boosted. It isn't the only thing that is taken into account, but a high PCSM sure helps, along with having a high college GPA, and doing well on the BAT (Basic Attributes Test) and Verbal, Quantitative, etc tests, which I think go towards your AFOQT (AF Officer Qualifying Test). I'm not too sure about the exact way it's done, this is very complicated.
But flying hours definitely are a plus in the USAF. If however you manage to get in without experience, the USAF will put you on the IFT programme to get you a paid-for PPL in 40 hours at an accredited flying school. You make the choice, you've got another 12 years to get it done over there.