Subhakarthi
I'm tempted to say nothing has changed between 2003 and 2007 in this regard, but you are maybe seeing different. There are a few alternatives.
Prefix the data from the database with a single apostrophe, will not show in Excel but will treat them as text. Try allowing the users to hit the database directly with a query. (Not sure if that route will make any difference though). If you set the data in a table on an html page, they could do a web query and there is a setting under options in the set up dialog to stop the conversion of dates.
The only other thing I can think of is to try some other mime types and see if that stops it.
It is an age old problem and there is little that can be done in some instances, but in defence, for some people the shortcut when typing their data in sheets to convert is desirable. Damned if you do...damned if you don't, that kind of thing.
I agree it would be nice to be able to 'type a column' or for Excel to recognise text data from databases, but it really is a numeric spreadsheet I guess, not a database???
Regards
Nick Hodge
Microsoft MVP, Excel
Southampton, UK