My question is besides the obvious lack of storage space is there any reason to upgrade these for gaming purposes. I don't store movies or massive amounts of data that needs to be moved around a lot. If so what are some recommendations.
Newer drives are all around much faster. Something like the WD Black 640gig or 1 TB are as fast as previous gen Raptors. You will see Windows and programs load faster. To me those old drives are going to be a huge bottleneck with that nice i7.
I can tell a HUGE difference between my older WD 250 Cavier SE16s and my WD 640 Blacks even without RAID.
You can keep the old hdd as extra storage on you computer but as anort3 said, your current hdd's will be very slow. new hdd are cheap and most of them are faster than what they where just a few year's ago.