My, 2x HDDs in RAID 1?????? Thast what yo defentelty should be going for RAID 0.
RAID 1 nowadays IS NOT BACKUP. The proper way to do it is with a external HDD. If anything goes wrong, your files are emedialty acessable by ANY machine (including Macs out of curiosity)
Now, of course putting the OS on a RAID 0 setup would be awesome, but for a better organized computer, is tottally fine to put OS and apps in one volume and exclusevely games on a second.
If you feel sad that your OS and apps are not on your faster volume, buy a OCZ PCI-e SSD revodrive, for the ultimate experience!