I just bought a 1Gb card for 1150 Rs for my nokia n70 and wanted to transfer all the app's to the new card. I previously installed most of the games and app's on the 128 Mb memory card that came bundled with the phone. So I tried doing the nokia back up on the nokia software that was installed on my computer but that didn't work.
So here a way to transfer your app and files from one memory card to another. Just got to the folders menu on windows and select the option to show all the hidden files and now put the old card into the card reader and copy all the files on to desktop even the hidden files. Then just put the new card in the card reader and copy them over and put it on the phone and restart the phone that's it.
All the installed applications settings etc work like before from your new memory card. It took sometime for me to figure it out so hope this will be helpful for someone.