Should work fine, especially with an IGP. P4 516 is 84w TDP and G0 stepping Q6600 is 95w. i965/P35 chipsets are 16w and P45/G45 is 26w thanks to PCIe 2.0. DDR2 is about 6w per 2GB stick and the hard drive is probably around 10w max.
Does your ASUS motherboard support Core 2 Quads at all? If it can support 45nm Quads then Q9650 only measures 72w @ stock despite the 95w TDP rating. I think they just didn't drop the rating because they didn't want to flood the market with heatsinks that didn't work with their previous chips.