As a consultant on data protection whenever you connect to a web server that offers a secure connection (shown by a padlock) you have an encrypted Secure Sockets Layer (SSL) between your web browser and the server, so as long as any financial transactions are done in this context then you should not be open to prying eyes even over an open wireless connection.
Its best practise to use WPA - PSK with TKIP or AES - some routers offer both.
You should not use WEP to be honest and yes if you change security settings you will have to renter the pre shared key (PSK) pre shared meaning your router knows it and when you type that password into the tablet/laptop it then knows it.
WEP is weak and if someone decided to connect to your router and "sniff" the packets they would be able to see the key and log into your network, then they could easily sniff the network traffic and obtain data if the connection between you and the web server was not using SSL as mentioned above.
The two factor authentication that Englishman mentions is something all my cards are registered with "Secured by Visa/Mastercard" and is a good deterrent against fraud.
There are so many ways to steal data now - you should consider buying some internet security packages but new threats come out every day - these new threats are called "zero day attacks" and the AV companies may not have updated their virus/malware database as yet so you do have to be vigilant against accessing bad web sites, of which once the page has loaded it has already infected your computer.
I could go on and on to be honest but I'd suggest you used a few different AV/Malware checking tools and give your laptop a once over. You should always watch for some of the internet "game" sites the free games that people play they are rife with malware!
Also final piece of vital data for you - you have two types of user accounts on your computer - Administrative and "user" when browsing use a "user account" then should some dodgy bit of code want to infect your computer it cant work properly because your account hasnt the administrative rights to edit the system files/registry.
So create two accounts - protect the administrative account with a strong password - car number plates are useful as passwords they are ot in the dictionary (although password hacking is quite easy to be honest) so are often harder to uncover. Try not to use your own now that I have mentioned this so openly!
Hope this helps.
Tone
