how to upgrade navision 4.0 sp1 to navision 2009

Hi we have developed an application for a customer 2 yrs back and now the same application should be used at another customer with small customizations so how to upgrade this.

Is there any tool for that

I would merge the objects from the existing customer into the new customer’s database, using a text compare tool. I hope you documented the modifications well, or it’s going to be a heck of a job.