The driver in AM7 is the newer version of the one most compatible with your system. The driver in AM8 supports your controller ONLY for XP, not Win2k3. If you want to test to see if it works with w2k3, then open M\AM8\ahcix86.inf
and change:
[ATI.NTx86.5.2]
%NapaDesc%=Napa_Inst,PCI\VEN_1002&DEV_4392&CC_0104
%NapaDesc%=Napa_Inst,PCI\VEN_1002&DEV_4393&CC_0104
%NapaDesc%=Napa_Inst,PCI\VEN_1022&DEV_7802&CC_0104
%NapaDesc%=Napa_Inst,PCI\VEN_1022&DEV_7803&CC_0104
to read:
[ATI.NTx86.5.2]
%NapaDesc%=Napa_Inst,PCI\VEN_1002&DEV_4391&CC_0106
%NapaDesc%=Napa_Inst,PCI\VEN_1002&DEV_4392&CC_0104
%NapaDesc%=Napa_Inst,PCI\VEN_1002&DEV_4393&CC_0104
%NapaDesc%=Napa_Inst,PCI\VEN_1002&DEV_4394&CC_0106
%NapaDesc%=Napa_Inst,PCI\VEN_1022&DEV_7801&CC_0106
%NapaDesc%=Napa_Inst,PCI\VEN_1022&DEV_7802&CC_0104
%NapaDesc%=Napa_Inst,PCI\VEN_1022&DEV_7803&CC_0104
%NapaDesc%=Napa_Inst,PCI\VEN_1022&DEV_7804&CC_0106
Then try to "force load" the driver into your running system and see if it works.
AM7: DriverVer=07/01/2009, 3.1.1540.151 (older, more compatible)
AM8: DriverVer=11/17/2011, 3.3.1540.26 (newer, untested)
Just because a driver is newer, does NOT make it better. Let us know how your testing goes.