First off, your going to have to give more details on the PC's of the LAN your trying to create. Second, your going to have to create a workgroup. Homegroups only work between windows 7 OS's when they work at all. Others have had this problem in the past, so searching further in the networking category is a good spot to see what others have done. I'm running a LAN with 3 XP, 3 Vista, and 2 win 7 with no problems. Some have had specific problems related to ethernet cards, others were simple fixes. what kind of router do you have too so we can get a clear pic....