Obviously I can not speak for the US system, but from what I have read here, and from ten years in the Army before becoming a cop, I can say that it certainly will not hurt your chances of a career in LE.
The discipline and training is a bonus, but the biggest thing you will get from being in the military is the life experience. I was 17 when I joined the Army, and although I had moved around a lot as a kid, and lived in the city, the country and everywhere in between, when I joined the Army, I was serving with people aged from 17 - 37, country folk, city folk, heavy metal fans, and arty types who would prefer a Monet exhibit to a rock concert. I moved to many different cities within Australia and lived in many differenet types of areas.
This was more beneficial to broadening my life experiences than the training and discipline and prbably more effective in giving me a better appreciation of dealing with people, which is a major factor in this job.
Just my .02 cents worth. Good luck.
"He didn't want to tell the cop he was on his way to the Butt Pirate Palace for a little two-step with Joe-Joe during the Village People marathon." - Cat_Doc
"Cause when your hourglass runs out of sand
You can't flip it over and start again...Don't blink..." Kenny Chesney
"Take care, never leave home on bad terms, watch your back and go home in one piece." - Aussie Nathan
"The batton in my jacket is hot like a porn actor to beat someone down." - Patchcop