"It would be great if I could do some hardware based filtering for GPO application based on things like CPU speed or drive free space"
This is a possibility with the GPO tools we have today. Using standard GPO tools and more specifically the GPMC. Thank goodness that tool (Group policy management console) is not included in SP2 WS2k3 and in WS2k8.
Here are some good starter links on some very basic WMI filtering