I recently found this app and am having trouble using it on my Vista Media Center.
It seems to install fine.  I have installed SpeedFan 4.35 and enabled logging, set the decimal separator to a comma and changed the labels to "Core 0 T" and "Core 1 T" as mentioned on the web page.

I get the following error in System Monitor at the configuration screen.  System Monitor / Settings / SpeedFan

SYSTEM MONITOR
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Could not read SpeedFan settingsRequested registry access is not allowed

thanks.

edit:
realized it doesn't allow access to the registry when logged in as another user.  I log in to my VMC using a MCE user.

When I logged in as Administrator, I was able to set my options and save them.

However, no data is shown.

edit #2:
Although I enabled logging, I forgot to enable logging on each item.. CPU 0 T, CPU 1 T, etc.
Now I get:

SYSTEM MONITOR
-----------------------
'temp' is undefined

edit #3 and Solved:
It now works.. I was using the wrong case.. the T needs to be lower case (just like the instructions say ) 

edit #4
Any ideas how to get this working with extenders?
I get the same registry problem as my original post.

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Vista Ultimate with TV Pack
Core 2 Duo E4500 @ 2.2GHz (OC'd to 2.9) / 4 Gigs Ram
c: 80 Gig d: 500 Gig SATA
Tuners: PVR-500 / HDHomeRun x 2 / WinTV 1600
Extenders: DMA-2200 / DMA-2100 x 2

Linksys V1 extender (for sale..anyone interested?)