should i get a new Hard drive?

hey,right now i have a single 7200 rpm 320gb seagate or western digital (cant remember which i ordered) hard drive.Would it be worth it to get another hard drive to use for my games, which have gotten too numerous to install all of them, along with my music, videos, general programs, and more. If so, whats the best hard drive i could get, in terms of speed, reliability, endurance, quality, and size, at teh price range of between $50 and $75 from newegg.