Question : How to keep connected to strongest wireless signal not the 'preferred' one.

I've got two wireless base stations.  One is the router and the other is a wireless extender, connected by ethernet cable.  Most of the time I am next to the router so have that as my preferred connection.  However, when I am nearer the wireless extender and have a good signal my laptop sometimes tries to switch back to the router, even though the signal is much poorer and somtimes drops out altogether.

How can I set my windows wireless netwoking to connect to the strongest signal of the two?  It seems as though you have to choose one over the other in the Preferred Networks control panel.  If I choose the wireless extender I'll have the same problem in reverse when I'm next to the router.

Answer : How to keep connected to strongest wireless signal not the 'preferred' one.

What type of wireless card is it? You might go to the vendor's website to check for software/driver upgrades. In the past I have used cisco aironet cards, which come with a software interface which helps the card hone in on the stronger signal and overides the preferred network settings.
Also, as a test, deselect allowing windows to manage your wireless settings and let the software that the wireless card came with choose the access point/extender