Sata Data Transfer Rates VS RPM

I am looking to buy a new HDD, my SSD and 200GB HDD is not even close to enough storage for me, so im looking for either 1tb or 2tb, not too sure on the differences in performance, newegg has a deal right now for a 1tb caviar black 7200 rpm for $120, but its only sata 2 interface, however i could pick up a 2tb caviar green drive with sata 3 interface, but there only 5400 rpm for $130 im mainly going to be using the drive for storage, backup and games, since my OS is installed on my SSD. what would be the best bet here based on my needs?

Media servers don’t really stress the disk all that much, except maybe for caching. Any drive, probably even one from ten years ago, could handle the read rate for a media server. There’s an easy way to estimate how much bandwidth you’d need to serve a file.

Let’s say you have a 720p rip on your machine, at 4.5 GB. This movie is 90 minutes long, and you want to serve it from the media server. So, at minimum, your drive needs to be able to read 4.5 GB of data in the time it takes the movie to play. That’s only about 0.85 MB/s.
Because the initial buffering is going to hit the disk harder, you’ll have a higher utilization there, so let’s say we need to load the first minute of data (about 50 MB) as quickly as possible, say in under 5 seconds. That gives us a peak speed requirement of about 10 MB/s.
Even the worst 5400 RPM drive should be able to handle 10 MB/s, and 0.85 MB/s is a pathetically light load.

Which is better a 5400 RPM or a 7200 RPMĀ  hard drive and why?

5400 is slower (doesn’t read and write as fast) but uses less power
7200 is faster, but uses more power.
Usually for a laptop 5400 is better.
So for Desktop 7200 is better.