Without Administrator rights it is going to be difficult to sort, but not impossible!
Since you have an XP Installation CD it may be worth attempting an XP Repair installation process. To do this you may need to change your computer BIOS startup configuration to enable Bootup from CD.
If you have not done this before the BIOS configuration menu is normally accessed via pressing a single keyboard key which will be indicated at the initial power-on screen, usually F1 or F2 for example. Then look for a Boot setting within the menus and set the CD as top of boot list.
Alternatively, some BIOS's are pre-configured to pop-up a BOOT selection menu by pressing F11 or F12 which may display very briefly just before Windows starts. If so, you can then select the CD from that menu which is a bit easier to do than configuring the BIOS settings.
When the CD boots successfully you will need to access and perform the correct repair options which will effectively replace all XP System files only and leave you other files intact.
A useful guide on how to go about this process is available here:
http://www.michaelstevenstech.com/XPrepairinstall.htm
Now assuming this all works for you and you get your system back looking ok, check your account status as per my previous post to see if it has Administrator status. If it is not Administrator then you are going to need to perform some more configuration actions involving creating a Password Reset / Administrator Account activation CD, something for a later date if necessary but as an example see:
http://pogostick.net/~pnh/ntpasswd/
Hope you can at least get the XP repair to work.
Let us know how it goes!