For the KT266A chipset, the AGP driver is part of the VIA "4 in 1" / Hyperion drivers.
http://www.viaarena.com/?PageID=300
http://www.viaarena.com/?PageID=403 - direct to 32 bit OS version
Note:
1. 4.51 are the latest
2. 4.43 arre suggested for older chipsets (including the KT266)
http://whitebunny.demon.nl/hardware/....html#vgaxabre
You may find the Xabre (also supports Sis315) driver more satisfactory - either the 3.11 (performance) driver, or the 3.57 - for some reason, they dropped everything above 3.10 from the official site.
There's a SV266A and an SV266AD - simple recognition, the "A" has TWO pairs of DIMM sockets (PC133 SDRAM or DDR), while the "AD" has ONE pair of DIMM sockets and ONLY supports DDR