access 97, SQL 2005

I am having issues with a UNION query. The query is prompting the user
for the apramter twice. I know if I create a form where the user can
type the parameter, I can reference the value from the form in the
query, but I am really not crazy about the idea of having to create an
entire form just to get this query to run.

Is there another way to have this prompt the user only once?

Here is my query:

SELECT dbo_tblJL_Main.MachineSN
FROM dbo_tblJL_Main
WHERE (((dbo_tblJL_Main.Customer) Like "*" & [Enter Customer Name:]&
"*"));

UNION SELECT tblTD_Main.MachineSN
FROM tblTD_Main
WHERE (((tblTD_Main.Customer) Like "*" & [Enter Customer Name:]&
"*"));

thanks!

-a