Best Platform Choice For Computer Science/Robotics Class?

The teacher of my computer science class (which has focused mostly on programming) wants to completely redo the curriculum to be more robotics centered, and he wants me to help. So, I need to try and find the best kit/components to start building and programming robots. If anyone here knows where we should start, I would really appreciate some help. I was looking at Nerdkits, and since my teacher wants the projects to be expandable into anything we want to do, this seems like a good solution. I have one, I haven’t used it much, but one of the things I noticed is that it might be a little intimidating for students just starting out in the class.
Another choice that I want to look into is Arduino. I really haven’t looked into this at all, but I’ve heard of many projects that use it, and it sounds like an easier platform to learn, but still flexible to any project.
The third choice I was looking at was Lego NXT. I know this is completely different from the other two mentioned so far, but I’m thinking this may be a better way for students to start out and then move onto the Arduino or Nerdkits. There is also a firmware that will let you upload Java code onto it, which would work out well since my teacher already knows Java. Since I have one of these, I could also donate/sell it to the school, which would reduce the cost for the school.
I will keep researching these and looking for better options, but I would also appreciate input from you guys! So if you know anything about this, or of a forum where I should ask for help, please let me know. Thank you for any help!

EDIT: 1,000th post, Yay!

Lego NXTs are awesome. Very easy to program and build
I don’t have any experience with Arduino but it seems that you’ll need to know some physics and chemistry + how to solder.
Arduino is C/C++ based