2 hdds in raid 0 for the os, the rest as normal drives with games, films ect
for this would i need a second controller? or can windows 7 see the none raid disks left on the controller
Windows-7 sees what the motherboard and bios sees. What motherboard do you have? I think they all will allow you to have both raid and non-raid devices attached.
But... Raid-0 is not very effective for the OS. The OS does lots of small random reads and writes. Raid-0 allows two drives to do sequential processing of large files well. You might want to read about raid-0 here:http://faq.storagereview.com/tiki-index.php?page=SingleDriveVsRaid0
The best performing device for the OS is a good SSD with trim support.
The next best is a 1tb drive or a velociraptor.