Remember this is just over the local network, you aren't peering over the net.
It works by creating a local cache and stores files that it has downloaded in that cache for a short period of time. Windows sends parts of those files to other PCs on your local network or PCs on the Internet that are downloading the same files.
Considering the fact that just about everything MS puts out is hacked or exploited, I think this would be a great way for computers on a local network to spread malware and infections. Creating a local cache of exploited or infected software and then having other machines rely on them as trusted updates is what concerns me here. I know some people will say that MS probably already thought about that and put in safeguards. But we have Windows 7 which has been out for 6 years and it's still getting dozens of exploitable software fixes every month, so what does that say about MS ability to safeguard from anything ?
it's tempting to get a second router
Looks like MS are really looking out for us techs
Yes... we use:
cable modem >> 5 port switch >> 1 line to our business router/network + 1 line to our customers & guests router/network...
Everyone knows our guest account password, and because it has it's own subnet and wan IP there is no cross-over.