The DHCP server function in it can probabaly support 255 address, the your performace will start dropping off long before then. I would say when you start getting above 12 node then you would probably want to start using intelligent switches instead of hubs pluged into your BEFSR41 router.
Much bigger than 32 and you should start thinking about taking the step towards a real Cisco router in the center running the show, and you may be better off using equipment from the same manufacture.
And yes there will be tones of cheap geeks saying things like - "I just load one linux box to act as firewall/DNS/DHCP server and then I had 200 Netgear 24port hubs plugged into it and it all worked fine." and if these people ever darked the doorway of a real services company they would be laughed at.