Yes. You can install office  2007 along with Office 2003 without uninstalling it.
But only one thing is that, you can have all necessary office components like
Excel, Word, Powerpoint, but you can have only one instance of Outlook. Either
you should have Office 2003 Outlook or of 2007. This is the only point in that,
rest is ok.

As your friend told getting learnt and working with 2007 is bit tuff than 2003.
But you will get into it soon.

I repeat you can install office 2007 without uninstalling office 2003. So you
can have both office 2003 as well as office 2007 installed on your computer.

Enjoy with both office versions.

If you want to cross check my points, please visit www.techtree.com and search
for offce 2007 where you can see the snapshots also where they had installed
2007 along with 2003.