I ultimately had to change the authentication settings on the Samba server to get reliable connectivity. Turns out that Win98 in VirtualBox isn't an amazing option for me anyway, though, because 3D acceleration is not supported. It may be useful for non-3D games, but it looks like I'd have to set up a Win2K VM for 3D ones and hope that they work better than they do in Win 7. No, I don't have any specific games in mind at this time. It was just an experiment because I had the pieces laying around