Sorry for getting this old thread alive.
But I am also an user of a MacBookPro wth GeForce 8600M GT, in fact my machine specs are the same as cobrax posted before.
I am also suffering exactly the same refreshment problems as he showed.
Using Mac OSX 10.5.8.
For instance sometimes when pressing TAB to open the operators menu it appears white, empty, or when I have it open and press any letter to open the submenu with operator beggining with that letter it also appears empty, just a white space.
Also the shelf has problems when hidden/unhiden it.
And finally the other noticilble problem is when dragging a pane's edge to make it bigger/smaller sometimes it mess all the Houdini desktop.
So seems that there are still some problems on the Mac side for 8600M cards.
Thanks

@ Mattis:

I'm sorry to bring up this old thread again, but I've searched the forum and found nothing about my problem:

How do I write a $ in a houdini expression in OS X, Snow Leopard with a MBP?
Also, is it possible to make equivalent to middle-mouse click in houdini?

A Dollar sign is made by hitting shift+4

Middle mouse button is not available by default, however, you can get this tool called “Better Touch Tool”. google it, download it and you can set up several different gestures or finger combination clicks to do different actions.

I use the three-finger click more middle-mouse button.

o.0

when i bought my iMac, I specifically choose the model that specify Nvidia video card, so far Houdini runs very smooth on my iMac.