Scrolling speed with the scroll wheel on my Logitech VX Nano is significantly faster in my Windows XP Pro guest than on my Leopard host. I understand Fusion treats the mouse as a generic PS/2 mouse, but wonder if there's a vmx setting or any other method of configuring scroll wheel sensitivity? Adding usb.generic.allowHID = "TRUE" and using Logitech's drivers would presumably fix the issue inside the guest, but would make switching between the guest and host very painful.
I've tried setting "Roll the wheel one notch to scroll the following number of lines at a time:" to 1 (the minimum) in Windows XP's Mouse control panel. In this case, with the mouse in precision (click) scrolling mode each click scrolls up/down anywhere from 5-10 or more lines in Excel, and with the mouse in smooth (frictionless) scrolling mode I'm able to keep it to 1 line in Excel if I have a very steady finger... however significantly more sensitive than in the host OS. Bumping the control panel setting back up to 3 (the default) means scrolling up to 30 or line lines in a click in precision mode and makes scrolling 1 line at a time basically impossible in smooth mode. So, apparently I just need an option for sometime like 1 lines per 10 clicks. 
If there isn't a way to configure the sensitivity of the virtual scroll wheel, any thoughts on some combination of scroll settings in the host and guest that could even things out a bit?