in my experience with winXP sp1, you can
not cancel out of winXP auto detecting/installing wizard upon reboot after removing drivers via add/remove proggys. In order to cancel out of auto detect wizard (which you need to be able to do in order to get a clean driver install) you must first delete the inf's and pnf's.
this is a one time only procedure So....
ATI:
1. unplug nic card or modem from net (physically unplug)
2. create system restore point (just to be safe)
3. remove ATI driver from add/remove programs then remove CP from add/remove programs
4. reboot into
safe mode (F8 during boot up)
5. if you've never deleted the ATI inf files from windows (ie search ati*.* and delete) or if you're connected to the net, you'll not be able to cancel out of windows automatically finding new device and installing drivers for it. You must first get to the place they you can cancel out of windows installing drivers for you... so at this point, let winXP auto install drivers. If you can cancel out of wizard then skip the rest of this junk and run that cleaner utility above! if you can NOT cancel wizard then:
6. go to device mgr->display adapter->uninstall and/or remove ATI display adapter but do not reboot
7. Open windows explorer and delete c:\ATI and c:\program files\ATI
8. start->run->search c:\windows for ati*.* and delete all (though not any bookmarks or other ATI files that you have and want to keep

. **Be sure your search includes hidden files and subfolders too**
9. empty recycle bin and reboot
10. you should now be back into windows and if you're unplugged from the net and have searched and fully deleted (emptied recycle bin) ATI*.* files, you should now be able to cancel out of windows automatically installing your video card drivers. Just cancel out and run this cleaner program now. if you still can not cancel out, repeat steps 4-9.
nvidia
1. unplug nic card or modem from net (physically unplug)
2. create system restore point just to be safe
3. remove nvidia from add/remove programs
4. reboot into
safe mode (F8 during boot up)
5. On reboot into safe mode winXP SP1 will auto detect and install drivers. Just let it do its thing. If you can cancel out of the auto install hardware wizard then skip the rest of this crap and run the above cleaner utility now! If you can NOT cancel out of auto detect wizard then...
6. navigate to device mgr->display adapters->highlight nvidia and click uninstall or remove but don't reboot
7. search c: for nvidia*.* and delete all folders and files (with exception to ie folders or something like that.)
8. now navigate to c:\windows\inf by default folder is hidden so you need to go to tools->folder options->view->show hidden files and folders. You need to go to the NV*.inf and PNF files. Delete each one. Both inf and matching PNF. get all NV. To be sure they're nvidia you can open inf with notepad and see mfgr as nvidia. Maybe around 5~6 inf's and matching PNF's.
9. empty recycle bin and reboot
10. you should now be back into windows and if you're unplugged from the net and have deleted the NV INF and PNF files, you should now be able to cancel out of windows automatically installing your video card drivers. Just cancel out and run the above cleaner utility. If you still can not cancel out, repeat steps
**note - utility program does not delete c:\ATI or c:\program files\ATI nor c:\nvidia. If you want those gone too (which I do) then you have to manually delete them. Just do that before/after running cleaner but before reboot after cleaner.