Traditional Sidekicks (Danger OS) saved NOTHING to SIM Cards.
There has been an option available for several months to back up your data to either your memory card (not the sim, but your SD Card) or to your computer. e-mail does NOT back up, but things that ARE: Contacts (Address Book), Calendar, Notes, To-do lists, Photos (that are saved to the device, not the SD Card), & Bookmarks (from the Web Browser)
See more info here: https://my.t-mobile.com/Support/SidekickDataExport.aspx?WT.z_nav=HPExportContacts
If you have already disconnected your sidekick data service, and it has been less than 3 months, you can contact T-mobile, and they can temporarily turn your Sidekick data service back on and hopefully your data will still be there so you can back it up. when finished, call T-Mobile back and they will turn it back off.
You can then use Google services to import your data (especially calendar, ToDo & contacts) to their service. Calendar transfers very easily. Contacts are somewhat sketchy but any data it can't figure out is saved to the NOTES section of the record/contact which you can manually change to fit their data fields.
If you want e-mails transferred, you have to manually forward each 1 to another e-mail address. I read here: Community - User Blogs - sktocliq2 - Powered By Danger
that if you do this from the Website (Sidekick Desktop Interface), and use Firefox, there is an add-on that allows you to save all links on the page as HTML files. this would automate the process...
QUOTE: "If you have been trying to find a way to backup your tmail email before giving up your sidekick, then since it isn't a POP email service, you have to either forward all the emails to another email account or go to the sidekick Desktop online and save the html files that are the emails. Easiest way is to view 200 emails per page, and use the Firefox web browser with the addin DownThemAll. That will download all the html links on the page in one shot, so you get 200 of your emails at a time. You can find DownThemAll on the web with a quick search. Good luck."