workgroup and homegroup are two different things.... you dont name your homegroup... all you do or have to do is to enter the same password when joining a homegroup, on all desired pc's. Tho they all have to be on same workgroup, i'm guessing thats MSHOME. j
The Homegroup will only work with existing 7 pcs that i know of, not sure bout 08 server or the upcoming 7 server ( would imagine so). Tho sharing files thru workgroup with the hybrid pc network is still possible without the use of a Homegroup.