MSP 7 Upgrade won't install over VS 8

[Rockmin]

I just bought the download version of MSP7 and am attempting to install...

It comes up with the message that I must have VS 5, 6 or 7 installed???

I have VS 8 installed! I tried pointing it to the CD drive (with the VS8 disk) but it looked at it and came back with the same message. Must have VS 5, 6 or 7.

The download link stated it was for all VS owners (no mention of version 8 or 9 not working).