I don’t have Mavis Beacon, so I can’t directly answer your question.
However, just a bit of information that may or may not be helpful.
A lot of programs that work on Win XP do not work on Win 7… but a lot do. Also, there are different versions of Win 7. There is a 32 bit version of Win 7, and a 64 bit version. (well, there are more versions, but they are all either 32 or 64 bit.) The 64 bit version is basically more advance, but is less likely to have older programs work on it. So something that works on Windows 7 32 bit might not work on Windows 7 64 bit.
I wish I could tell you if the program works or not… just wanted to let you know that just because it works on XP doesn’t guarantee that it will work on Windows 7.
That said, I run Windows 7, 64 bit, and so far have only had one thing I own not work on it.
What I would do is do a Google search with a phrase something like
Mavis Beacon Windows 7
and see what information comes up.