I don't know of any freeware that is similar to MBM5, maybe someone else does and will post a link to it. I guess your problem with getting NBN5 to work is that work on it stopped back in July IIRC. Hence, you mobo may not be in the lsit of supported mobo's at installation. The only thing I can think of is to play around with the selecting the various sensors listed till you find the one that works. If you think you have selected the right one, you can check by rebooting and looking in BIOS (temps will be slightly diff after rebooting, but close enough to confirm).
Fern
EDIT: Maybe someone with your mobo can identify for you the proper sensors to select. Look at forums for your specific mobo.