You should consider using one of the toolkits, many of them have something akin to Dojo's storage http://ajaxian.com/archives/dojostorage-offline-access-and-p... . This buffers you from the implementation details and as newer browsers come along they are able to update the implementation to take advantage of newer browsers built in databases, while providing you with the same backwards compatible API. If you have not chosen one, I recommended you take a look at Dojo, if you are going to build a full on web app and jQuery if you have lighter requirements.

Side note: we are really starting to side track this thread, why don't you email me (in my profile) or add me to your contacts in Skype (if you use Skype) that way you can hit me up on any questions you have.

I did send an email yesterday, the title is "Your approach to web development. I realize now that the title might look like SPAM :) Anyway those questions were answered, I'll send you another one.