I recently modified my XP setup to trick my laptop into thinking it was running XP Professional, when in actuality it was running XP Home. This enables several features which were still on my system, but just not enabled. For example, I can now connect to a domain (well, not really, since I don't have a domain controller) and use lusrmgr.msc to configure users and groups. I now also have my Security tab visible in Properties dialogs.
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And now for the information you've been dying to hear since you started reading this article: how to do it. First, you must go into c:\windows\i386. On some systems this may simply be c:\i386. Now see if there is a folder called winntupg in there. If there is, you're good to go. Otherwise, get it off another Windows XP CD. It doesn't matter whether it's an OEM copy that came with another computer; it also doesn't matter which edition that disc is. Just get that folder into your i386 directory. Now open up Registry Editor, select HKEY_LOCAL_MACHINE, and then click File > Load Hive. Select the file called setupreg.hiv in i386. Type in a temporary name, and then open that new key in HKEY_LOCAL_MACHINE. Go to ControlSet001, Services, and then setupdd. Now double-click (Default), and change the 01 and 02 in there to 00's. Click OK, select that key that was created when you loaded the hive, and then go to File > Unload Hive. Click Yes, and then close Registry Editor. Now, look in i386 (on your hard drive) for a program called winnt32.exe. Run this program. When asked, choose to upgrade. Enter your product key (yes, it will be accepted) and install. Now all that's left to do is wait, and then go through that Microsoft Out of Box Experience thing (with the blue question mark icon which moves around the screen giving assistance.) Even if you have an OEM copy of Windows, it will ask you to activate, but don't worry: it will do so just fine. Some features will still be missing, but that's simply because the files for them don't even come with XP Home. If you really want them, copy them off of another computer which runs an honest-to-goodness XP Professional.
