The lady you want to contact is Michell Perez at CAST Software [email protected] and/or use the automated renew function in the Membership Panel on the CAST Website.
R24 blows R22 out of the water, and almost all of the nasty bugs Video and Render related (including the Vista redraw-fail one) are gone. Oh, and you can farm renders off to networked PC's to save your local processor.