So here's taking on AmazingHenry's suggestions for modding "About This Mac".
Here's a bit of dark humor for "Shock and Blaaaah":
(Putting on my asbestos flame-suit since it will no doubt proved to be unpopular)
Anyone have a suggestion for a different statement for Steve Ballmer ? ;P
Maybe I should upload the PSD.
And here, on a lighter, more aesthetic note:
(Which really has nothing to do with OS X historically)
If wanted, all three About This Mac tifs are zipped together @ Mega:
https://mega.nz/#!UNFXQDgQ!Kgt0nDSH4Oxswoza0fZgiMABk6NSgEvsqVuj9dex8io
They are actually pngs with the extension changed to tif.
Originally PSD then to png via "Saved for Web and Devices..."
I went this route since merged PSD Layers saved to Tif were bigger in size.
Probably could have done it differently but I don't have eyoungren's Photoshop expertise

They did work in my Quicksilver's Leopard install.
Caveat: Use at your own risk. Use Duplicate command for backups.
I copied/backed-upped the original About This Mac (MasOSX.tif) by copy/pasting it to the desktop,
and using the Duplicate command for an additional copy.
This is the route I took for Leopard:
Drive > System > Library > CoreServices > loginwindow.app --> Right Click: Show Package Contents >
Contents > Resources > MacOSX.tif <-- Copy/Paste to desktop for backup.
Rename the chosen modded tif: "MacOSX.tif". Replace Original MacOSX.tif with modded tif by drag & drop,
[Authenticate], [Replace], type your account password. RESTART.
EDIT: If Mega gives your older browser problems, here are the modded About This Mac tifs.
They are originally pngs so as pngs I should be able to upload them here.
Once downloaded, change the .png extension to .tif & the name to MacOSX so they'll work in the Resources folder.