Unable to uninstall Office 2003 after installing Office 2007

Recently I bought a new Windows 7 laptop that came with pre installed Office 2003. Last week I already bought a genuine Office 2007 copy. Now as I wanted to use 2007 I installed it over 2003 without uninstalling it. Now, though I can see only office 2007 apps in my program list, but office 2003 is still visible installed in my Add and Remove Programs. I tried to uninstall it by clicking on remove button but it is giving me an error saying:

'The installation source for this product is not available. Verify that the source exists and that you can access it.'

I tried deleting many times but every time the same error. How can uninstall office 2003 ? Please help.

You should have first removed it and then install Office 2007. Did you installed the new one from Disk or you upgraded it ? if you have upgraded it should have removed it automatically. Anyway what I can suggest you is either you will need to arrange Office 2003 installation disk to install it from your system OR you will need to backup your data and reformat the C drive and install back again everything.