misdemeanor question?

hello,

I am in the process of finishing my last two prerequesite courses before applying for FSCJ's summer 2011 nursing program. So far I have done fairly well with keeping all my grades at A's and B's. However I am aware of the background checks they do when you apply for the program, and I am very concerned at where my status will be due to this:

About two years ago I made the unwise decision of riding in a vehicle with a complete moron who had illegal substances in her car. We were pulled over and searched and both charged with possession. They handcuffed her and let me go with just a "written arrest" for a single misdemeanor charge of marijuana. However I appeared at my set court date and completed the required one time offense course to have the charges dropped. I have heard so many times that even though charges are dropped or you have them ex-sponged, anything you apply in the medical field your record doesn't really "clear", meaning dropped charges can still be pulled up. And if I am accepted into the nursing program, what about the doing the clinicals, or even after graduating how will this affect me finding a job? So please if anyone has any knowledge or advice for my situation let me know, I have been very stressed and concerned about this.