FYI, I'm attaching two very small patches that get the r300 driver working with my AGP X700 card.
Adam
Index: shared-core/drm_pciids.txt =================================================================== RCS file: /cvs/dri/drm/shared-core/drm_pciids.txt,v retrieving revision 1.29 diff -r1.29 drm_pciids.txt 23a24 > 0x1002 0x5E4B CHIP_R420 "ATI Radeon RV410 X700PRO"
Index: src/mesa/drivers/dri/radeon/radeon_chipset.h =================================================================== RCS file: /cvs/mesa/Mesa/src/mesa/drivers/dri/radeon/radeon_chipset.h,v retrieving revision 1.1 diff -r1.1 radeon_chipset.h 38a39 > #define PCI_CHIP_RV410_5E4B 0x5E4B 121a123 > CHIP_FAMILY_RV410, Index: src/mesa/drivers/dri/radeon/radeon_screen.c =================================================================== RCS file: /cvs/mesa/Mesa/src/mesa/drivers/dri/radeon/radeon_screen.c,v retrieving revision 1.47 diff -r1.47 radeon_screen.c 576a577 > case PCI_CHIP_RV410_5E4B: