If your computers have Wireless N cards, you will see an increase in transfer speeds from PC, to PC on your LAN if connecting to that WAP instead of your current Wireless G router.
I personally, would set it up so that the WAP is on one side of your home where the Wireless G signal is weak, and treat it as a repeating WAP to help get full strong signal through out the house. But if you get a full signal through out the home, disabling your current routers Wireless, and setting the WAP up, would increase your overall LAN speeds over the wireless, but only if your wireless cards also support N, if they only support G, you won't notice a difference.
Please note though, that this will NOT increase your bandwidth out to the internet.