i thought momentus was the name of their sshd line, but that link is definitely a traditional drive, so i might have mixed up my product lines. this one is an example of an sshd:

http://www.amazon.com/Seagate-Laptop-2-5-Inch-Internal-ST1000LM014/dp/B00B99JUBQ/

the key part you're looking for in that description is where it says "Integrates NAND flash with traditional hard drive storage"

Ah, sorry. This: http://www.amazon.com/Seagate-Laptop-2-5-Inch-Internal-ST1000LM014/dp/B00B99JUBQ

Not saying to get this exact one, but it is what I put in my personal system and my PS4. Its cheap but effective plus a good size.

That's a decent machine, your main bottleneck is the hard disk drive which at 5400 RPS is very slow. You can move to an SSD, but the downside is that it will be very expensive to get decent storage. A 500GB SSD will cost about $200 (though just noticed that this one is available for $150 at Amazon http://www.amazon.com/dp/B00OBRE5UE/?tag=pcpapi-20 ).

That will be very fast but you will run out of storage at about 10 AAA type games (not as much of a problem if you're playing mostly indies).

Another alternative (which us what I did with the same system) is to upgrade to a hybrid drive, an SSHD that will give you 70% of the speed bump for about 30% of the cost per gigabyte. This 1TB drive is around $80 http://www.amazon.com/dp/B00B99JUBQ/?tag=pcpapi-20 .