Before becoming a member of this site, i saw only one round-about fix for xerox phaser 3117 printer compatibility with windows 7! That was using a Samsung model driver instead of the non-available xerox fix/update.
Now there's good news from both ends: Xerox and Win.7! In fact the credit goes to win.7 more than Xerox. I could download an update which installed the UPDATED DRIVER ie the route of the fix was via windows update as suggested in this excellent review by MS! : Find and install printer drivers for Windows 7
I just now printed three test pages in disbelief! This .zip update from Xerox : Phaser 3117 File Download
Thought this will save the printer being replaced un-necessarily and in the bargain save some dough! Hope this helps!