I recommend going to this site:
http://www.heavens-above.com/It'll be a pretty dim object to spot, compared to the ISS, but I hope to manage it sometime this week. Assuming the Air Force doesn't fiddle with the orbit.
As I recall, the X-37B does have a fair amount of fuel for orbital manoeuvres.
Thinking about the X-37B, X-51, and then all the technologies that will hopefully be tested in orbit and at the ISS over the next 5-7 years...pretty exciting times, eh? Shuttle may be ending, but the future looks bright.