The latest version of the NWC Viewer (2.26) includes a significant fix for Windows Vista. Recent versions of the NWC Viewer did not correctly detect the presence of NWC1 and NWC2 on the host Windows Vista computer, making it much less useful as a *.nwc launch pad. This new version corrects this problem. You can get it here:
NoteWorthy Composer Viewer
http://ntworthy.com/nwc2/viewer.htm