You can set a couple of package upgrade options in the designer through the SSIS options page (Tools -> Options...)
These defaults will be used anytime you upgrade a 2005 package through the designer.
See my post about the Upgrade Wizard for more details on these options.
You'll also a couple of other things on this page:
- You can set the default language to use for script tasks /components
- The "comfirm" delete option on the left (the typo has since been fixed!)