To answer your question we need lot of deatils about your budget and expertise of your manpower (wheather they are comfortable with *nixes)

linux is a great platform to run oracle as compared to windows
currently my comapny runs windows as well as linux.there are certain limitations when ur runing oracle under linux

like ops(oracle parallel server) is not available
oracle enterprise manager is not available

for windows we have ops as well as gui oem
minus the stability of *nix.but linux comes for free

in absence of detailed information of your set up its very difficult to advise you.hope whatever advise that is offered above helps.

hrishi