rolf wroteAn SSD for your system partition... You can get a small one (64G) for $100... and it's not blazing fast but you'll still feel the difference. On my system boot time and launch time for big apps was reduced by half. But my HD were a bit old.
It's particularly useful when you're working and have many apps opened.
If you have more money you can buy a faster and bigger one (you'll probably need more than 64G for games anyway) - there are some real fast ones but their prices go into the $200/$300 and they're not available everywhere.
Too bad your two drives are different sizes, otherwise you could have striped them (software RAID 0) for better performance.
To be fair your system seems OK. On an old system used for work, an SSD can do wonders and give it a new life. But on a new system used for gaming, I'm not so sure!
If you're into overclocking, I'd give water cooling a thought.
An SSD, for a gaming system, would primarily reduce loading times and help with streams from data hungry games such as World of Warcraft. For the system, according to the accounts of its users, it's a night-and-day difference from hard drives. Not all games can be stored on small capacities, so it's most beneficial to store those that benefit the most.
For me at least, striping two hard drives, without backup, is a bad idea (I'm assuming you mean they should be backed up or they should not contain critical data). One drive fails, the other has half the information, which is useless. IMO, HDD RAID 0 is very beneficial if they are drives to store games only. Saves should be backed up or better yet, stored in another volume. Paging file should be allocated to the RAID setup since that's where it would benefit the most. IMO, an SSD as a system drive + 2HDDs in RAID0 for games is a quite good solution. For me, it remains that using a single HDD is enough (+probably an SSD).
As for the SSDs, they are available, and ROG store is willing to get some of the best. Crucial M4 is such an example. SATA 6G is where most of the benefit from modern SSDs rely. Since the OP has a 6-series chipset, then he should have SATA 6G.