forget the cracks and injectors etc... this is the BEST WAY:
1) start > run > "regedit" (without the quotes of course)
2) go to the key:HKEY_LOCAL_MACHINESOFTWAREMICROSOFTWindows NTCurrentVersionWPAEventsOOBETimer...and doubleclick on it.
Then change some of the value data to ANYTHING ELSE...delete some, add some letters, I dont care...just change it!now close out regedit.
3) go to start > run > "%systemroot%system32oobemsoobe.exe /a" (again, dont type the quotes)
4) the activation screen will come up, click on register over telephone, then click on CHANGE PRODUCT KEY, enter in this key: JG28K-H9Q7X-BH6W4-3PDCQ-6XBFJ.
Now you can dl all the updates without activating,
and the Genuine Microsoft Validation thingy wont bug you no more!!
Works with most WinXP versions though ther r some exceptions...