With Win7 or Vista it’s better not to install Bryce to Program Files (x86), as Windows protects those folders, and Bryce requires some content to be in subfolders of the application folder.
I think this is a question of preferences. I never install anything on C, it’s reserved exclusively for the system. On D are text and graphics applications, on E programming languages and my web workspace, on F data, images, renders, documents, on G backups and workspace for Bryce content and on H a backup of the system. I have that organised in this way since Win 98. True backups are on the 6 network drives. If anything fails, there’s only one drive to restore.
Others feel comfortable having everything on C.