you need to find out what those files were that didn't copy.
If you need to reinstall to find the names, just install to a different windows directory (call it winxp or something instead), this way you will not mess up your current installation - just delete this directory later.
If you're reinstalling, wait till you get a copy error, write down the file names and paths then skip over them.
(If you already know the names and paths, then just boot the installation cd and wait for the option to use the system recovery console and skip the next bit....)
Once the copy process completes, the system will restart. As its doing so, you need to boot from the cd again, don't let it boot from the hard disk else you're screwed.
When the installer starts up again, you get an option to use system recovery console. this is a dos-like interface which allows you to copy files off the cd, decompress them automatically and put them where you need them. So if you wrote down the files and where they need to be, you can simply copy them back using recovery console -
ie: copy rktools.ch_ c:\windows\system32\rktools.chm
do this for as many files as you skipped and you will be sweet.