Office 2003 Reload

A virus on my PC required me to download the data files and wipe the hard drive. Using the System recovery DVD, I got the machine back to original status, but now my full version of Office 2003 is back to the 60 day trail version. I DIDN'T keep the registration code when I upgraded to the full version. The PC (Gateway) has the software on it, it just needs to be activated with a valid key. Since I did it once in the past (about 2 years ago), do I have to buy it again? Also, Microsoft doesn't want you to use Office 2003 and tries to up you to 2007. Do I have a problem or am I going to have to buy software AGAIN?

Thank you for your reply question. I purchased the PC in 2005 and didn't activate the 60 day trial of Office until 3 years later. When I did start the trial, I registered and paid for a full version of Office 2003 via the Internet all at once. The hard drive got wiped 2 and a half weeks ago. Office 2003 is no longer supported by Microsoft and the PC (a Gaterway) is out of warranty and support won't help me there, either. It's a little frustrating when I don't have the registration key! I'm using the same PC, so it's not even a matter of transferring it from one PC to another.

Thank you for the guidance. I'll try to see if they will help.