Wireless N issue with laptop (4965AGN) and Linkysys300 n router

I used to have a "G" wireless router(linksys) and a sony Vaio PC with Intel wireless link 4965AGN card. The network connectivity was fine although the signal strength was low. I recently bought a Linksys 300N Wireless router and expected to see improved signal strength as well as improved data rate. To my surprise there was no change.
After going thru the settings and other information found that my network connection was still "G". I switched the router to "N" mode only and then could not connect the laptop to the router.
There must be a setting or such to change so that my laptop will will change from its "G" mode to "N" mode.
Any help is appreciated

Hardware:
Laptop: Sony Vaio VGN-FZ180E with Intel wireless link 4965AGN
Router: Linksys 300N wireless router