You might want to try a repair install for Microsoft Office. Otherwise, you will have a lot of security updates to install -- although that is still better than a reinstall. Why not try it with one of the smaller programs that won't have security updates first.
While you're at it, you need to update Adobe Reader 8.3.0. You can install the latest version of Adobe Reader from
http://www.adobe.com/products/reader/ .
Only after you are finished and when you are certain you won't be attempting any of the earlier System Restore points (i.e., from mid-August as referenced above), you need to remove ComboFix. Doing so will implement cleanup procedures and also to reset System Restore points:
Click Start > Run and copy/paste the following bolded text into the Run box and click OK:
ComboFix /Uninstall Note: In the event you wish to contribute to the ongoing development of ComboFix, the developer is accepting donations via PayPal.
You should also update to IE8, which is the highest version supported on Windows XP.
Please let me know if you have any additional questions.