two nic in w2k but confused

i have two network cards installed on my win2k server. they are connected to seperate networks A & B. but it seems that the os takes one of the cards as the default, such that whenever i try to access network A , it works fine, but accessing B (evenpinging) times-out. unless i disable interface card A. then B would be working. but then when i enable A back, i would not be able to connect to B again. is there any way to access both networks simulteneously?