Well most people today are getting minimum 80-120gb as their relatively very cheap. And I think that amount is needed seeing what type of applications we are facing nowadays.
Main Rig in Tech Specs
Alienware Area-51 m9750 - Intel Core 2 Duo T7200 2.0GHz, 4GB DDR2 667MHz 4-5-5-9, Samsung 160GB Hybrid 256MB Flash Cache 5400RPM, nVidia GeForce GO 7950GTX 512MB
Toshiba Satellite L650-13M - Intel Core i5-410M 2.26GHz, 4GB DDR3 1333MHz, Seagate 320GB 5400RPM, ATi Mobility Radeon HD5650 1GB
Acer Aspire 5750G - Intel Core i5-2410M 2.3GHz, 8GB DDR3 1333MHz 9-9-9-24, Hitachi 750GB 5400RPM, nVidia GeForce GT540M 1GB (DDR3 ver.)