SFZ+ and Square I and the effects were free only through the Cakewalk store, but seem to be no longer available.
SFZ and Square I are still shipped with Sonar.
Fwiw, here's link to a
Square I user manual.
Triangle II is still lying around :
http://web.archive.org/web/20140327103800/http://cakewalk.com/Products/triangle/T2111.exe