The best chipset cooler I've heard of so far, is this one:
http://www.swiftnets.com/products/mcx159-CU.asp
It accepts a range of push-pin hole spacings of 2.05" (52.1mm)
to 2.41" (61.4mm). Measuring a photo of your motherboard, shows
the push-pins are roughly 2.14" (54.3mm) apart. You can use a
ruler and measure the spacing for yourself, better than I can.
The really unfortunate part, is the Swiftech heatsink would
have to be mounted on a diagonal, and one corner of the heatsink
would probably bump into your graphics card.
It is possible the Zalman passives would also be a problem.
http://www.zalman.co.kr/eng/product/code_list.asp?code=014
The Zalman NB32K is 37mmx37mm. On the diagonal axis, it would
be 37*1.414=52.3mm . I think that leaves just enough room to
squeeze a push-pin in there. But, again, the heatsink would
have to be installed on an angle, and cannot be installed square
to the video card slot. You'd have to cut one corner of the
heatsink off, so it would clear a long video card.
http://www.zalman.co.kr/eng/product/view.asp?idx=180&code=014
If you use one of the Zalmans, personally I'd want a fan strapped
to it. I have no way of knowing what the TDP for the Nforce4 Ultra
is, but the heat output could be substantial since one chip does
everything on those boards. It's your motherboard