Save button that lets you chose save location, but defaults to certain folder

I'm going to see if I can explain this decently. Right now I have a button in my workbook that saves the workbook to the "My Documents" folder using a specified filename.

I need the files to save into certain folders... for example, if you are Joe, you would want to save to C:/folder/Joe, Mike would save to C:/folder/Mike. The name folders are already created.

Now I can't actually guarantee the names of the folders (for example, Mikes folder might be called "Mike R" and Joe's could be called "Joe Smith_01" or something..), and many users will be using this file.

So what I would like it to do is when you click the button to save, the 'save to' window automatically brings you to "C:/folder" so you just have to pick your folder name. I was wondering if Excel can do this? It sounds more like a windows thing to me. I know you can change the default folder it saves to for all workbooks, but that isn't really what I'm looking for.

Any suggestions?

Thanks!