Suggest you look at the DD-WRT script "autoAP". This may give you some ideas.


From the wiki
"AutoAP is a script that continuously scans for open Wi-Fi connections, tests them for validity, and connects to the strongest signal. If the connection is lost, the script scans again and finds the strongest valid signal again, and maintains a continuous connection to the internet in a mobile or portable environment. The script paremeters are highly configurable, including ability to configure secure connections. "

Parameters include:
Filters to avoid logging onto specific SSIDs
Filters giving preferential logging onto specific SSIDs, including encyption key values


Script can also verify that successful wifi connection also allows internet access.

I would love to see something like this adapted to run on the Nokia tablets.

See
http://www.dd-wrt.com/wiki/index.php/Autoap
and
http://www.dd-wrt.com/phpBB2/viewtopic.php?t=6575