Which graphic card to repair my 24 inch Imac of 2008 ?

Hi !

I'm using an 24 inch Imac of 2008 : 4gb ram, 500gb HDD, core 2 duo @3,06gHZ, Nvidia 8800GS.

My graphic card burn and she is near dead. I want to chage it, but I don't know what will be compatible.

Can you help me ? I'm thinking the Ati HD2600 of an 2008/2007 20 inch Imac or an Ati 2400 of an 2008/2007 20 inch Imac will work, but I'm not sure. If anybody have tried, can he testify ? Is there an other graphic card that is compatible ? I don't want to take an new 8800GS, because it's unstable for long term use.

Thanks !