Hey, I was pretty much in the same boat as you. I'm starting the accelerated BSN program at Hopkins in June and went up there for the first time last weekend from Texas to get things figured out. The first place I saw in the city was awful, I was afraid to get out of my car. I honestly thought about not going, but once one of the other new students drove me around and showed me the nice areas of town to live, I felt much better. I ended up renting a place in Washington Village, however, Charles Village, Mt. Vernon, Mt. Washington, Bolten Hill, Fells Point and Canton are nice as well. The rent is the cheapist is Charles Village and Washington Village. I'm planning to ride the Metro (subway) to class everyday, or I'm also considering riding my bike (I need to drive the route more though, I'm not sure it's totally safe).
Some of the other new students rented places in Cresmont lofts in the Cresmont area. Personally I did not feel safe there, we ate there one afternoon.
If you want roommates that are nursing students, you may consider checking some of the postings on accelerated BSN group's yahoo group at:
http://groups.yahoo.com/group/jhuson_accel2005/ Several people are looking for roomies. I think the traditional BSN program also has a yahoo group started, you may want to check that out too. I realize these are groups for undergrads, but the accelerated students must already have a bachelor's in something else, so you're unlikely to get stuck with someone who is not serious about school.
Good luck, feel free to PM me if you have more questions.