I impulsively bought a WD15EARS (Western Digital Caviar Green 1.5tb) hard drive today and I am kicking myself now that I realize its a 5400rpm drive... (or they claim its between 5400-7200 but im not so sure i believe it). I also have a seagate 750gb 7200rpm drive that I use as exernal storage at the moment. Now it would be alot easier to just use the WD drive in my new built and avoid copying about 650GB of data to it in order to use the Seagate, but I'm wondering if that will impact the gaming performance of my new computer (AMD 955, Radeon 5970, G.Skill 4gb ram)?
This is a GREEN drive, so logical it runs at 5400rpm. That's a huge benefit to a drive that stores mainly large files. But not really great as system drive running Windows.
However, as games load mostly sequential data, you can also opt to just stick with your green drive. As you watch the benchmarks, you can see the Green drive beating older 320GB 7200rpm generations due to the higher data density. It only falls short of 500GB-per-platter 7200rpm disks for the system disk task (random IOps).
In short, i would just keep your drive. Its running cool, silent and decently fast.