I wanted to reply to this, to post what happened after trying this update. I decided to junk vista and install 7 anyway, and planned to use the 7 loader rather than the slic bios method as it didnt seem to work. So i trashed the hd, created new partition and installed from scratch. Low and behold, now the new slic 2.1 shows, and has activated successfully! That suggests to me that this is somehow tied to the bootsector of the hd? I know this is in the bios.. but why would it suddenly work after trashing the hd? Ah well.. I can confirm it works ok now!
It was probably due to having a Vista Loader/Activator replacing the BIOS info in memory after boot up.