Sharing folder on XP

I work in an office where we currently have two Win2000 PCs that act as shared file servers, people can access these and map the shared folder as a drive on their own PC (we call it the ‘M’ drive). This mapping is necessary as this is GIS data that people are using in their map projects and the program needs a path name. Win2000 only allows 10 people to share this folder at one time. We are in the process of converting to XP and I was told at one time that XP allowed unlimited people to share the folder. However, I’ve been reading posts that indicate that only 10 are allowed in XP as well. Is this true and if so, has anyone come up with a workaround? This is a federal office, so buying out of the box software to overcome this isn’t really an option. Thanks!