Excel 2003 and 2007 Compatability Problems

Ive got complete office 2007 and excel 2003 installed on the same computer.
1. i need 2007 for some of the advanced features
2. i need 2003 for the reporting program i use.

the trouble i'm getting is that i want everything to open in excel 2007 by default.
i know i sounds simple, folder options OR right-click properties,
but this doesn't work,

if i set it to the excel 2007 logo (right-click properties) it wont open at all.
i get the hour glass and nothing.

however if i open 2007 first and then open a .xls it sometimes opens.

is there anything that can change these to default OR any other help


Please