Login Screens and Login-Studiothingamajig

Hey all, I was wondering about changing my login screen, but in question of the toolset of programs used to do it. I've done it once before on my WinXP comp, and it require any studio or 3rd party software, it was an exe that I replaced (after carefully backing up the original copy) over a system one, from reading around, suggesting that I've altered the kernel. Now, from reading around, that is a risky way of doing it, and service packs can alter if they work or not, but are they still supported? I'd like to change my login screen, but not with the song and dance of software changing the display. (I like how the exe method doesn't really add an extra process to the computer, but just replaces it, where with this, and windows blinds, for example, covers over anything and takes a bunch of RAM I don't have.)

Any responce is welcomed, thanks!

~WerelWulf