Radeon HD 3870 open source driver support?

[Dennis Jacobfeuerborn]

Hi,
what is the current state of support for the Radeon HD 3870 cards? I intend 
to buy a new card soon and I'm aiming for either a 3870 or an NVidia 9600GT.

On Linux I'm only looking for decent 2D support which basically comes down 
to good performance in Firefox and when playing back DVDs and other videos. 
3D isn't important though support for compiz would be nice.

Regards,
   Dennis