Thanks Matt,
As I am not a Sonar user, it sounds like Forte is still my best option for running under 64bit Windows 7. (Barring the hardware synth route).
I always replace the VSC sounds with better synths once I have exported the BIAB Midi arrangements to my DAW so the BIAB midi synth quality is not paramount, but it needs to be good enough to do the BIAB styles justice when auditioning and arranging in BIAB. I am sure that I must have passed up perfectly good styles in the past just because the Midi synth they were playing through in BIAB didn't sound great. For instance I have learned over time that any style with an overdriven electric guitar will sound pretty poor through the VSC but will usually sound OK when converted into, say, a sampletank sound.
On the other hand I have always found the VSC bass guitars, pianos (electric and acoustic), and the string sounds to be pretty usable.
I have never got around to buying Forte but from the forum discussions I get the impression that it is on a par with the VSC, better on some instruments and worse on others.
I have always stuck with the VSC because a) It's free, b) It integrates pretty seamlessly with BIAB, and c) It's fast in operation (I had a pretty poor experience with Bandstand in this respect). I guess that I will have to take the plunge with something else (probably Forte) when I upgrade to 64bit.
I haven't given up hope that PG may bundle something great with BIAB as a 64 bit VSC replacement.
Regards, Aubrey