Can't really see what your problem is here - as long as
the date is safely passed from the client app to the server
(which it is as you are using ado parameters) then there
is no problem.
The way the date is displayed in SQL server is controlled
by the language setting(read up on @@language and
sp_helplanguage) Internally the date is stored as two 4-
byte integers. The first 4-bytes are the days since/before
1 Jan 1900, the other 4-bytes are the number of
milliseconds since midnight.
As long as you format the date to your required format fro
display in the client app, then where is the problem?