I own a small business there are only three computers in my office. My windows xp comp that I use only for my business stuff (insurance), my wife's computer (win 7) and my Mac that I use for non business stuff.
The router/modem is an AT&T u-verse supplied variant, I am not sure what model it is I will check tomorrow.
I am used to seeing the two besides Mshome and Workgroup as those are the other two comps I mentioned. Also my Mac hasn't been moved in ages, there have been no changes to my setup or anything like that.
Also thanks for the replies, it kinda freaked me out when I saw those other comps in my shared area.