+10 to any and all "if you have no alternatives, take the job" and "in this economy, take the job" advice posted in this threak.
Depending on the industry, it's pretty rare for many companies even to be willing to negotiate a starting salary. And in this job market, they have all the power. So you're pretty much SOL there. Were I in your shoes, I'd just suck it up, accept the job at the salary level you were offered, and cultivate a network / do a great job in your position. You cultivate the network both to develop professional contacts and to sew the seeds of future exit options, should you decide you need them. And you perform well at your job because, well, that should be obvious.
You're in a better position to negotiate an offer when you have some legitimate experience under your belt and are a proven performer. That can't happen right out of school, unfortunately, unless you were summa cum laude at Harvard or something. Also, generally speaking, you're in a better position to negotiate when you have multiple options. For example: Company X is offering you $46k, and Company Y is offering you $50k. It's fine to see if X will match Y in such a case, because you have precedent. (Just don't attempt to start a "bidding war" or go back and forth to try to raise the stakes, because that will get you a big, fat middle finger from X and Y).