some info should anyone read the original post (by me! ;-)... I've found some info on another site after more 'research'! - (
http://www.icrontic.com/faqs/kt7faq/kt7faq.htm) which has a lot of great info on Abit KT7-100's, including using this (and other Abit m'boards) with certain graphic cards.
I found a page there that informed me (via info from the Guillemot/Hercules support) that the Herc GTS PRO card I purchased specifically for the Abit motherboard does NOT work due to compatibilty issues with the m'board. There is a US phone number to call to exchange the card for a modified one that will apparently work with my graphics card.
There is also info on changing the 'driving control' settings in the BIOS which could solve other compatibility issues between m'boards and AGP cards.