Not sure I understand. Do you want to buy a bike to race or for recreational group riding? Do you plan on running track whether you get a bike or not?

Everyone's different so I don't know but I can't imagine what it would have been like to be in college and not have a bike. As far as biking versus running I think running is a pretty one dimensional, though cheap, sport. There is a-lot more to cycling and IMHO it is a healthier and more interesting life-long activity than running is. The folks on the running forums may disagree.