Hard drive for OS vs Hard drive for files

Hey there,

I was looking for opinions based on two different drives and which one would be better used for installing an OS (Windows 8) on and run programs, and which one should be used for file storage.

Here are the two drives in question:

Western Digital Red

• 3TB storage
• SATA3 (6gb/s transfer)
• 64mb cache

http://www.amazon.com/dp/B008JJLW4M/..._M3T1_ST1_dp_1


VS.

Samsung EcoGreen

• 2TB storage
• SATA (3gb/s transfer)
• 32mb cache

http://www.newegg.com/Product/Product.aspx?Item=N82E16822152245 (I know this one says out of stock but the drive was received a while ago)