Hi Diane,
Have you heard of the new [academicgames] listserv that NCSU just began in December? http://lists.ncsu.edu/cgi-bin/mj_wwwusr?user=&passw=&func=info&list=academicgames
It is geared towards university libraries that can address your specific questions. We have not gone down the PC games path yet or even console games with their respective subscriptions (e.g., Xbox Live) at the UCLA Library. They were grateful that I agreed to hold off on that despite how limiting that really is. They are currently testing 3-5 games we ordered and testing for any licensing issues.
On the side, I have received a lot of questions and concerns about the preservation of online games if we choose to go with that format, especially if we wish to have a "permanent" collection of games so I threw the question into the listserv and have been receiving lots of feedback, contacts, and readings to look into.
If you haven't joined this list yet, I think it will definitely be worth it!