Abit SD7-533 SiS Chipset upgrade

I have a SD7-533 running XP SP2 with the SiS 645 chipset to which I
recently added an ATI Radeon 9600XT AGP graphics card.

The install manual for the AGP card states that you 'must' upgrade the
AGP motherboard/chipset drivers. I've installed the new card and
everything appears to be just fine even though I haven't upgraded the
motherboard/chipset drivers.

I've visited the SiS website and found an AGP (Gart) driver for the 645
chipset plust the Abit site to get a chipset upgrade for the SD7-533
mainboard. I have not been able to find any instructions on exactly how
to apply the chipset upgrade on either of the sites or as a readme file
with the downloads.

How should I actually go about installing the upgrade(s)?

Please and thank you for any guidance.