Backpacking around Europe

I will (hopefully) be graduating from university in June, and a friend has mentioned he would like to go backpacking around Europe. This is something I would love to do before I settle into a carrer, and think this could be the only oppertunity to do it.

The problem is I dont have much money saved up, and my current job covers the bills and no more right now, so may not get much saved up (although im waiting to hear about another Job, which while it pays very well, it will be for 6 months so might not be able to go backpacking at all..)

Anyway, how much money would I need to go backpacking?

Anyone here done it, if so what advice do you have, especially about money, working while away and places to visit.