SIS have released a new AGP driver supporting most of their chipsets including:

SiSM650, SiSM760, SiSM741, SiS655FX, SiS655, SiS651, SiS650GX, SiS648MX, SiS648FX, SiS648, SiS645DX, SiS650GL, SiS650, SiS645, SiS635, SiS760, SiS755FX, SiS755, SiS748, SiS746FX, SiS746, SiS745, SiS741GX, SiS741, SiS740, SiS735, SiS661FX, SiS655TX, SiSM661FX, SiSM661MX... Version is 1.21
Dated: 01/04/05

SIS AGP driver

Note: The only updated AGP driver contained in this driver pack appears to be the 64-bit AGP driver, all other drivers are identical to those included in the 1.19 driver pack (1.17 in the case of WinXP)