You can run both together, I've done it before. As for it being hard, it's really not. You just have to get used to not having file menus, otherwise it's pretty self explanatory. If you were good with 03 or previous versions, you should be fine with 07. I'm not a huge fan of the new interface but it's really not that bad to get around with and once I got used to it I found it was actually more organized and easier to find things.