For your light –the HC96 (like the HC3, and HC1) have the Sony propriatary “AIS” shoe, not the standard accessory shoe like you had on your PC100. So your old light won’t work in the shoe. You’d need to either buy a AIS one, or buy a bracket you can attach to the tripod mount (like this)
http://www.keene.co.uk/cgi-bin/codesearch.pl?6831
This is a general issue with all the new Sony consumer camcorders… eventually I think there will be AIS to standard shoe converters available, but they are not currently (there are a few people making “homemade” ones).
Mark