I hit the 15 hour mark before the DOS window stopped responding
however i find that the launcher used to use about 150 megs at the start of the game and for every person that joins it use around 10 more megs of ram (per player) but after this last lock up and a PC reboot i find that the launcher is using 350 megs of ram at the start up and then 6 people joined my server and the ram usage jumped to 414 megs.
So i am guessing that the game uses 10 megs of ram per player
so basically you just need 1.28 gigs of extra ram (beyond what the OS is using) for a 128 person server