>What do you mean running side by side?

You can install and run both of them w/o affecting each other.

>And what exactly does foxuser.dbf do?

See http://msdn.microsoft.com/library/default.asp?url=/library/en-us/dv_foxhelp9/html/abcd6537-eec1-4ede-a97c-138f27016aa2.asp