My 1.5cents worth...
I think the answers to the "pagefile" question have been changing as computers evolve.. On the one hand computers these days offer much more memory and faster disks.. but, depending on how you use your computer/your apps, you may also end up running many apps that need much more memory. If you wanted to keep an eye on a metric for your machine, you could always keep any eye on the Physical Memory Usage on Performance tab in Task Manager.
Tho my personal view of it:
1. Disks are quite large these days. Allocating 10-12GB is still worth it and a small price to pay to be sure of performance
2. But i, for one, go one step further. I don't allow Windows to manage my pagefile, Rather i allocate the full amount i think would be needed and allocate it all upfront. Reason: A defraged pagefile will also give better performance. If windows manages it, it would increase in chunks allowing for fragments.
Tho... these days i understand Windows 7 defrags page files (where XP didn't) but still i've managed to allocat PgeFile on new installs and achieve 5GB+ in one contigous chunk! (so never need to worry about fragmentation unless i ever needed more memory)
In any case, is up to you..