Should work, with a few quirks. I'm not sure any DLLs will share the same names; hopefully not.
Do you currently have the full Office 2003? Then you might have to selectively un-install it - retaining the Outlook 2003 part. Or you could try skipping that and just install 2010 separately (in different folders) and allow both Office versions live concurrently.
Do you have Word as the editor for Outlook currently? That may not work with 2010, so you might want to de-link that first (ie, edit Outlook stuff with its own editor).
What OS do you have? Windows 7 or earlier?