Help Wanted - Using Video Games in the Classroom

I remember when I first started blogging and reading other teacher blogs about two years ago, Clarence was working on a very exciting project with his students involving Sim City. I've always thought it would be both fun and productive to do something similar in my history classroom. Lucky for me, my school had some software money that needed to be spent by the end of the month or we would loose it, so I ordered a few copies of both Civilization IV and Age of Empires III. I'm planning on using them during the last month of the year with students who took the Global History Regents exam this week and did well enough to not have to worry about a retake (the rest of my students will be reviewing for the Regents Exam).

So in essences, I want to create a project using these games that also serves as a culmination of my students' two-year study of Global History. The scope of both games seems ideal for this. Right now I am imagining something where students play the game and then keep a running diary or blog of their achievements, maybe with a short story component added for the final product. These ideas are pretty abstract, for now at least.

I was just wondering if anyone out there has used these games, or others like them, in their classes and could help me out - Did it work out alright? What type of more "traditional academic" work did students produce from the experience? What road blocks, if any, did you encounter? What can I do to make this a meaningful experience for my students? Even if you have never used games like these, do you have any ideas to make this work well?

Any advice will be greatly appreciated.