John,
If you can, please make it possible to unzip it on any logical disk in the system, not only in C:\, and don't hardcode the disk in Inno either.
Many people usually have at least one (or more) much larger logical partition(s) and install additional physical disks to keep data on. I, for one, have them all the way down to M:\
Such people get nervous being forced to install anything extra in C:\ which is a system disk where the ever growing \WINDOWS resides and where there's always too little space no matter how large the disk.
Whenever you're making a Windows install, I think it will be reasonable too to include the SB<->VB/COM/OLE stuff in it as a standard. VB6 still is and will continue to be very popular under Windows for as long MS Windows is available at all.
(No, not really but thanks anyway. I think FBSL already has its own COM layer and can communicate with VB/VBA by itself. Perhaps it might need some extra polishing but it certainly won't be me to engage in that activity. There's so much interesting stuff around, and one's life is only so short... )