It really depends on how far and how often you plan to travel. If you're planning to zig-zag your way throughout Europe, going from capital to capital, traveling far and often, the rail passes can be helpful. If you're just moving slowly in short little steps, the rail passes probably don't make sense. Chances are, you're probably doing something in between. What you need to do is to roughly sketch out your planned route, add up the cost of the major train legs of your trip, and compare that to the cost of the rail pass. Check out www.bahn.de for schedule (and some costs, especially for German trains), www.seat61.com and www.ricksteves, which has a nice section on rail passes and a time/cost rail map.
Dave