Crystal XI is no longer sold. You would have to get either Crystal 2008 or Crystal 2011. You need one license for each person who will be designing reports. I
think you can distribute report like you're currently doing without having to pay extra, but you would need to verify that.
The runtime/designer that comes with Visual Studio 2008 or can be downloaded for VS 2010 is Crystal 10, so there are some new features that it's missing. Also, I find the designer component in VS to be clunky and sometimes difficult to use - I much prefer creating my reports in Crystal itself when I can.
-Dell