Porting from D5 to D2009 - prologue

I have to admit I am looking forward to looking back at this project.
300.000+ lines of code, using numerous third party components, a sophisticated in-house ORB sitting on top of BDE with several designtime components, built-in version control for SQL statements and tight Oracle integration. Dozens of input forms and hundreds of reports.

I am not quite sure where to begin...

Should I convert to D2007 first, or go directly for D2009?
Advice would be appreciated.