>> all Radeon X1300 to X1950 cards with AtomBIOS *should* work.

> how do I know which x1300 and x1950 has atom bios?

If it's a card for x86/x64 Windows/Linux PCs (so not one for PPC/x86/x64 Macs), it has AtomBIOS.

> what about the Sapphire ATI Radeon X1600XT?

"X1300 to X1950" is a range and includes any X1600.