we're developing an asp application for a database but we keep on getting conflicting dates; on my machine (the server) it is returning US format dates and my colleague's maching is returning UK format dates. We're both accessing the same SQL Server and both of our machines are set on Windows to English - United Kingdom.
If you're using different SQL Server Logins, check that the default language of both Logins is the same. One of you may be using 'English' and the other 'British English'.
You could change any SQL queries to format the DateTime fields in a particular country's format (see Convert). However, this'll convert the DateTime field value to a character type which is not always desirable.