That should be ok, I'll be creating the new database using SQL server management tools, not ms-access, I already know I can get basic connectivity from MSaccess to a 2005...

I don't know if there is a SP difference, this KB article references both the SP and dbo type problems, so it might be linked. http://support.microsoft.com/default.aspx?scid=kb;en-us;253180 

Where is the DML operation being executed? In VB, from bound forms or from direct access to data objects?

If it is in VB then you can use standard VB error...

Hmmm, I could see a nice SQL profiler task happening for each server logging all actions carried out under your user id... Should thicken the swamp nicely!

Your focus needs to be on security on the SQL server. Any users that connect to the database should only have the rights necessary for them to do their job....

The alternative as mentioned earlier is to use xact_abort

SET xact_abort ON

BEGIN TRANSACTION

----Do your stuff here

COMMIT TRANSACTION

SET xact_abort OFF

xact_abort defaults to OFF so if an error occours inside a transaction it does not...

looks like the sum and square are the wrong way round i.e. sum of the squares and square of the sum...

In access you have

sum(([cur]-[avg])^2)

and...

The quick and dirty way is to cast from nvarchar to varchar then back to nvarchar, then compare with the original...

cast(cast(myfield as varchar) as nvarchar) myfield

Should be fine...