Have you checked to see if the Sony support website has Win7 drivers for the Vaio VGN-N17G?
WR2, it appears not. It seems that the possibility to upgrade only exists for Vista > Win7. Though there is something at the bottom of the page about upgrading from XP to Win7 by migrating all files http://windows.microsoft.com/en-US/windows7/help/upgrading-from-windows-xp-to-windows-7
. I'm running the 'Win7 upgrade advisor' diagnostic.