To play with you brother:
if you have two computers, LAN would be your best bet but niether of you would be able to play with other players at the same time. individualy one of you at a time could play without the other and with ICO players. (if you live together i dont think SD or IC has a problem with that, if your not i am not sure...) By logging into IC with one(shared) account, you could each then have your own (or multiple) "handle" or game name which each has its own record.
For two installs on computers you own. In other words, if I wanted to play with my son on our LAN that would be ok.
You cannot however have it installed on your computer in New York and expect to play online with you brother in Seattle. Get it?
the Monk
ok i butchered a mod install, and didnt back up all nessecarys and had to reinstall, does this mean i have used up my two legit installs? or does this mean if i install SINS on my wifes computer and my daughters computer in addition to my labtop, only two of them can connect (via LAN) at a time? i was intending on doing this once i fix on of the aformention computers.