Update Query Taking 23 seconds

Question

I am not sure if I am in the correct location or if I should be in the SQL forum but here is my question:
I have an update statement that goes out through SQL 2000 through a local linked server to another SQL 2000 server on my machine. When I run the update in Query Analyzer it takes less than a second. When I run it in my C# code using the SqlCommand object and parameters it takes me ~23 seconds. If I remove one of the parameters it goes down to ~15 milliseconds. Has anyone heard of this happening?
The parameter that I remove is a simple char(10) column that isn't the primary key and is used in the WHERE statement. There isn't an index on the field.
23 Seconds
Update table Set column = @val WHERE field = @field AND other = @other
15 milliseconds
Update table Set column = @val WHERE field = 'values' AND other = @other

Answer 1

Evan:
Try executing the query that follows and list the results:
set showplan_text on
  Update table Set column = @val WHERE field = @field AND other = @other
set showplan_text off
set statistics profile on
  Update table Set column = @val WHERE field = @field AND other = @other
set statistics profile off
The SHOWPLAN_TEXT will give the estimated query plan and the STATISTICS PROFILE will give the actual query plan for your query.  You can also try the same thing for your other query.  Also, give us the table definitions for (1) all indexes associated with the target table, (2) the PRIMARY KEY of the table and (3) any UNIQUE constraints associated with the table.  This will give a strong view of what is going on with the query.
Dave