WinXP in particular has an automatic "System Restore." If this is turned on, a backup of your registry, including the infection, is likely to be copied back after you run the Norton procedure, as soon as you reboot. If you turn off System Restore, all old copies of the registry will be immediately deleted, so it can't come back on you.
Start - Settings - Control Panel, scroll down and double click on System, Select the System Restore Tab and put a check mark in the "Turn Off System Restore on all drives" box. (Turn it back on after you get clean.)
If you're worried about needing a "go-back," make a manual copy from regedit. Start - run, type regedit, hit enter, chose File-Export, and put a copy of the registry somewhere else (where system restore can't find it). If you need it, double-clicking on the .reg file will put everything back.
Since this malware normally comes as part of some other program you download and install (often without knowing it) you may need to think back about what you may have allowed to be downloaded, and look for it in Add/Remove programs. If it was part of a program, that program will probably quit working if you remove the malware, so you might as well just uninstall the program.
Most anti-crud programs are safe, and if one you trust finds something you should let the program remove (or disable) it.
Some malware of this sort comes with an uninstall, if you can find it. The problem with this one is that the uninstall may have the name of the program it was embedded in.
You should ALWAYS try Control Panel Add/Remove Programs before trying to manually remove pieces, since you're much more likely to get everything that way.
Manually deleting individual files is a last resort, since that may "break" the uninstall scripts. Sometimes the "last desparate act" that works is to go back and get "reinfected," so that Control Panel's Add/Remove programs can rebuild the script and will be able to do a real uninstall. That's the normal procedure for Kazaa's spyware components.