Please install the following:
Graphics driver
Audio driver
Ethernet driver
Chipset drivers
BIOS update
Latest patch of MTA:SA
Latest DirectX runtimes
Provide another dxdiag log after installing.
Also, please install Windows XP Service Pack 3.
His drivers are already up-to-date.
Uninstall both MTA:SA and GTA:SA.
Then delete the MTA:SA and GTA:SA folders if they were not completely removed during the uninstallation process.
Then delete the contents of C:\Users\\AppData\Local\VirtualStore\Program Files (x86)\Rockstar Games\GTA San Andreas.
Now reinstall both GTA:SA and MTA:SA