Office 2003 disk not installing

Hi

My laptop has Office 2007 installed, but I want to install Office 2003. I bought what appears to be a genuine Office 2003 off ebay (apparently genuine packaging, product key, holograms etc), but Disk 1 is very slow to read, autorun does not operate, and ultimately I am not able to install Office 2003.

Is there anyway around this, ie do I have to uninstall 2007, or is the likely answer that I have bought a fake product?

Cheers

pvr325i