Based on bombadil's experience, it looks like even XP users should first try the software supplied with the oximeter. If that doesn't work, completely uninstall it and restart Windows before trying other software versions. I think the "+" only applies to the 50D/50D+ pair. The models I know of are: ...

Connecting a CMS 50D+ (50D-Plus) pulse oximeter to Windows XP This relates to the 50D+ pulse oximeter made by Contec Medical Systems (CMS) and sold under several brand names. It has data storage and computer-connect capabilities for data monitoring and uploading of stored data. The CMS-50D+ currentl...