Hiya,
www.microsoft.com has lots of articles on this issue. The first part of the date/time number (before the .) is the number of days since December 31, 1899 (I think) and the second part is the number of seconds past midnight of the day (I think).
This is usually found in a SQL Server database, and not Access. How did you get it there?
Did you work this out for yourself? It looks like it.
mmcdonal