Funny you should post this as I was about to post the following...
Was just in touch today with the National Archives at Kew regarding ORBs on DVD.
Contact Mary Leong at Mary.LeongATnationalarchivesDOTgovDOTuk confirms that they will copy ORB microfiche reels onto a CD or DVD at GBP 25.00 per reel for Bitonal and GBP 30.00 per reel for Greyscale. Separate charges apply for the CD or DVD.
I've ordered two sets of ORBs on DVD in the past and it's a heck of a deal - so easy to use once copied onto a hard drive.