Nope... CDA won't work with SF5. That's the reason I decided not to upgrade to Sound Forge 5. I stayed with SF4, which does support CD Architect.
Ernie
Don't forget though, that CD Architect 4.0 can work "alongside" Sound Forge 5.0, not from within. CDA can dock to SF4.5, but with SF5 you have to open CDA seperately. However, the two installations can exist peacefully.