I've seen several references here to 100 GB discs being "insanely expensive" and $40 to $50 each. I'm here to say that that is not so.
I just bought two different brands of them, 10 disc spindles, for $6 to $10 a disc off Amazon. (I'll let y'all know how well they work.)
I have been using 25 GB BluRay discs to archive image files (I'm a photographer) for some time now. And yes, BD-R discs are more expensive than hard drives. But they are also expected to safely hold data longer, too. I am worried about the possibility the drives needed to read them won't be around forever, but that is an issue with any media you choose. You have to be prepared to copy all that data to the next-great-thing at some point.
As to the OP's question, Roxio Toast will span disks. As long as you keep swapping discs in/out of the burner, It'll keep burning. But I'm a Mac guy, so I dunno what to use on a Windows machine.
While we're on the topic, a tip for my fellow Mac users who find pulling data off deteriorating CDs to be frustrating due to the Finder giving up part way through the job instead of scavenging all the data possible whenever it hits an error, I've found Chronosync to work well, as it doesn't just give up, but keeps digging past fatal file errors.