The Radeon 9600 has an AGP interface - no AGP slots on your chosen board. The
Asus A8V ($69) would be a solid 939/AGP-compatible board at a good price.
As far as a heatsink goes, quieter is better. A small 40mm hsf is going to be spinning real fast (read: LOUD) to do the work of a larger (92mm) fan running at lower rpm. For a socket 939 board, I would recommend either the
Scythe Samurai Z ($29),
Arctic Cooling Freezer 64 Pro ($30), or a
Zalman CNPS7000B ($30).