in XP (no service pack) you have to replace it in two different folders. $windir$system32/ and $windir$system32/dllcache/ (second should be first) . when windows says you can not replace the file, rename the original file (shell32.old or so) and then paste your altered version into that folder. then windows file protection asks you to put your XP cd in the cd drive. choose cancel. then it asks you if you want to work with the unauthorized files. choose yes. then reboot and it should work.
you can also replace the files with the commandline. here are some tutorials on how to do this:
http://www.neowin.net/forum/index.php?act=ST&f=34&t=44566
personally i replace the files from Linux. i have a dual boot system here. XP needs to be on a FAT32 formatted drive for that.
two very important tips: ALWAYS make backups. do not touch important system files with ResBuild from TGTSoft (it fubars everything), use ResHacker instead.
recommended site for resource hacking:
http://www.virtualplastic.net