Should I Raid or not?

Hello everyone,

I recently bought a 2TB Seagate Barracuda 7200rpm Hard drive and also received a 1TB WD 7200rpm hard drive as a gift.

In my current build I have a 128GB SSD that I run my OS off of, a 300GB WD 7200 rpm that I'm removing and giving to a family member, and a 500GB 6200rpm 2.5" hard drive that I throw on backups, pictures, and movies.

I was thinking of Raiding either the 2TB and the 1TB together or the 1TB and the 500GB hard drives. I was wondering if you can even raid 2 different speed hard drives together or if it just increases the failure chance. I was also wondering if it was even worth raiding? I use it mainly for Gaming and Virtual Machines.

Any suggestions would be helpful.

Thanks in advance!