The error message pretty much says it all - you are attempting to SET the value of a column defined as a money datatype to a character string value. This requires an explicit conversion. Your UPDATE should look like:
SET yourmoneycolumn=CAST(yourstringvalue AS money)
SET yourmoneycolumn=CONVERT(money, yourstringvalue)
Make sure that the conversion can in fact be done, since if your string data doesn't 'look' like a money type, you'll still get an error. You will have to edit the string before you use it in the UPDATE statement to make sure it is a proper numeric value.
Custom Apps, Inc.