I'm thinking about getting a 24" iMac. Just wondering if it is worth the extra £200 for the one with the faster 3.06GHz processor, 500gb HD and a 512mb graphics card?
The nVIDIA 8800GS is a much newer card and has much more room for improvement in future OSx updates than the ATI 2600 does.
If you are going to be keeping your iMac for a long time its well worth the extra considering Snow Leopard will most likely use OpenCL which will take advantage of the 8800GS.
It also really depends what you are going to be doing with your iMac for (gaming, movies, whatever).