Agreed on the fan grill cut. Do that to the front too.
From Zalman's compatibility chart:
9500 LED: ASUS P4P800 SE - 8.5mm Required (between mobo and power supply)
7000: List is of non-compatible mobos. Yours is fine.
7700: Not Compatible.
To see what you're looking at as far as distance, compatibility etc., you can use Zalman's chart as a guide. This is for the 7000, which is 109mmx109mm. They list the amount of distance you need from the edge of the motherboard retention guide to the power supply as 1.7cm. That means for a 120mm fan/heatsink to be able to fit, you'd need at least 2.8cm from the edge of the retention guide to the power supply.
It's possible that your case mounts the motherboard lower, but it's doubtful looking at the pictures.
From personal experience, the 7000 is a tight fit with that mobo and the 9500 fits with no problems.
Tuniq Tower - Excellent cooler. Won't fit (unless you can mount it with the fan pointing at the psu)
-z
EDIT: Don't forget to get a wire fan grill for the back. Don't need one for the front.
Also, what case fans are you using? You once you figure out a quieter heatsink/fan, you're going to notice the other fans in your system. Start with case fans, then GPU heatsink, then power supply. It's an addiction, I know, but it's worth it.