Why do you think AMD moved these cards to legacy status? Of course because they want you to buy a newer one so they can earn money.
- Stick to 12.04 LTS
- Stick to open source drivers
- Get another card from another vendor wich provides a longer support cycle
- Wait for a miracle that there will be a legacy update. (It's actually possible because of Valve and Steam).
CPU: AMD Phenom II X4 810 @ 3120MHz | RAM: Kingmax 2x2GB DDR2 800 @ 833MHz| MoBo: MSI K9A2 CF v1.0 (BIOS: 1.D)| GPU: Asus HD 6850 1024MB (DirectCu) @ 835/1135MHz | Display: L24FHD | PSU: PC Power & Cooling Silencer 750 Quad | OS: MS Windows 3.11 Pro x64