12 bottles a case, 60 glasses a case. Figure about one drink per person per hour. I'd say four cases.
You want, at least, two glasses per person = 240 glasses. 1 case = 12 bottles = 60 glasses. So you want 4 cases of wine, at least.
Depending on how much you pour, you will need at least 50 bottles, or just over 4 cases.
12 bottles is about 60 glasses, so I'd go 30 to be on the safe side. That's about 2 and a half glasses per person.
20 to 25 bottles, depending on how much you pour for each guest.