Excel slow to open

[bubbafish]

With the Microsoft updates a few weeks ago my Excel 2003 opens files very slow. When they are opened on 2007 they were slow until I updated the Trust Center so it would trust everything on that server. How do I get around this in 2003 since the files are used on both systems? When I say slow I am talking about 5 seconds on 2007 vs 4-5 minutes on 2003 for the same file!