It took me a while to dig out of the hole, but it really can vary.
For me, I was in the low 500s. I had seriously screwed credit, and couldn't get a loan to save my life. I got a car loan with a cosigner , and within 3-4 years, I've got a score that varies between 680 and 700, usually hovering in the high 680s, even with 2K in credit card debt and some old things hovering on the report.
Im aiming to pay the debt off before I start law school in 07 (hopefully by the end of this year.)