There are someslight differences between the chipsets.
There are several pages in the datasheet that refer to 945GC. Checkout Pg 15, 17 and 24 to start.
The FSB support is different and also the Max memory.
Please see this data sheet as it details the differences.
My Vista is saying the drivers for 82945G chipset, which I just downloaded, are NOT compatible with Vista... Your site says it will work, but Vista will not let me install... Is there a work-around?