I have a criminal damage to property (Class A misdemeanor, same as DUI, I think) on my record. I was 17 and busted a car window and slashed all four tires. Charged and convicted as an adult.
People aren't perfect. I screwed up and learned my lesson. Any employer who wishes to hold something I did when I was 17 against me isn't an employer I wish to work for anyway. I'd feel the same about an employer who wishes to hold one DUI against someone.
I wouldn't worry about your DUI affecting your job prospects for two reasons:
1. It's out of your control and you can't change it.
2. It probably won't hurt you.
I say #2 because most employers are only going to do a background check AFTER interviewing and deciding on a candidate. If they like you and want to hire you, seeing a DUI on a background check shouldn't suddenly make them think you're not a good candidate. If they saw child molestation, sure, that I could see hurting you. A DUI, heck no.
If they ask on an application if you've ever been convicted of a crime (most say felony, anyway, so you should be OK there), just tell the truth and maybe even bring it up in the interview. Explain what happened, tell them you plain screwed up, and let them know you're not a deadbeat and that it was an isolated incident which has no bearing on your job abilities.
If an employer wants to reject you after that, phuck them!
AUD 96 FAR 95 REG 94 BEC 88