no you can't set it to always connect to the strongest, you can change the preferred order of connection though.
open the control panel click on classic mode and then open network connections, right click on the wireless connection and select view available wireless networks.
Then on the left click change order of preferred networks, in the list of networks you can move them about using the move up and down buttons.
Windows will always connect to the highest one in the list first if more than one is in range.