Hi there ghostlygaming1,
What will be the main purpose of the drive? If you want to run games off of it, you should get a 7200 RPM hard drive. The drive that rolli59 suggested will be a good choice for that. Keep in mind that the hard drive speed influences only loading time not the overall game performance.
If you just want to store data on it, you can get less power consuming drive with 5400 RPM lets say.
Getting SSD for the most demanding programs/games + HDD for storage is a good idea too.
Cheers,
D_Know_WD