As a side note, I love WinXP for it's "tweakability".
There's probably not a single aspect of it that I haven't tweaked - the boot screen, the sounds, the visual themes and styles, performance aspects, running programs, default settings/programs.
I'd be up shit creek if something bad happened because my registry/system settings have been totally and completely overhauled. In fact you'd have no clue you were running WinXP if you were to sit at my computer and use it for awhile because there literally is nothing on it that I haven't tweaked. I can't even remember the last time I've seen the Windows logo or any kind of windows character/setting. hehehe
And it's removing the user logon prompt/welcome screen that I think is the best tweak I've ever implemented. I love being able to restart my computer (after a software upgrade or update, for example) and go get a cup of coffee or take advantage of the time the computer's starting up to do something else, come back, and find it at the desktop ready to go rather than having that middle step where i have to choose an account or enter a password.