Installing office 2007 student over a standard trial

My computer came pre-installed with a copy of Microsoft office, I
don't' recall which version, but it is expired and had Excel, OneNote,
PowerPoint, and Word.

I've signed up for night school courses, and the school lets students
download and install Office 2007 as a perk. Do I need to remove the
trial before running the installer?

Also, I've heard that Office 2003 and 2007 can coexist. I currently
have my old copy of office 2003 installed on Virtual PC with my old
copy of Windows XP professional, can I have both available on the host
OS?

How would I set that up? I'm much more productive with the old
version, but as I'm in IT I really need to learn Office 2007.