imcbmichaelb,
Per Microsoft:
Boundaries are used to assign clients to a specific Configuration Manager 2007 site and should be unique to each site. When defining site boundaries for sites, ensure that you do not define the same boundary for more than one Configuration Manager 2007 site. Doing so leads to a situation called overlapping site boundaries. Overlapping site boundaries are not supported and can lead to undefined results in Configuration Manager client behavior.
I think that wraps it up nicely for you.
Further reading:
Planning -
http://technet.microsoft.com/en-us/library/bb632910.aspxConfiguration -
http://technet.microsoft.com/en-us/library/bb633084.aspxThanks,
Ex