middle-mouse button hotkey/graphics question

Hey guys

A couple of questions if you have time…

I was wondering if moving up to the Radeon 5870 in my Mac Pro (from the 5770) would bring any benefits for Cubase - it seems quite sluggish when scrolling around a large project, a problem I never used to have when using a GTX285 on my windows box. Does anyone have any experience with the difference between the two cards? I know Apple say it’s 70% faster, but I wondered if this genuinely applies to Cubase, or if it’s simply a benchmark gain.

Also, I wondered if there was a keyboard shortcut way to invoke the middle-mouse-button mode of moving around the main arrange window? It’d be great if you could hold down a key and pan around the page in this mode as it’s a very handy and intuitive way of moving about the project.

Thanks for any tips!