Updating the Exported .xml file before uploading to a different WP installation

I have tried exporting an entire blog and then importing it to another blog and am extremely happy with how well it works.

However, in my old blog, there are several links I’d like to change on a global scale. I tried editing the .xml file in Dreamweaver, but this caused the new WP site to error all the posts (it worked before I made my changes).

Any advice on how to edit the export file?