Alrighty, theres an issue with Service Pack 2 for Windows XP that sometimes causes it to rename all skins downloaded to .zip files. This is NOT a difficult thing to remedy, but there is no permanent fix. All you have to do is rename the extension of the file from .zip to whatever the coresponding extension should be. For example, a WindowBlinds skin would be .wba, and a DesktopX object would be .dxpack. If your computer is NOT showing the extensions of the files, you need to go into Folder Options and tell it NOT to "hide the extensions of known file types." Then you should have the extensions visible to edit them.
Bootskin: .bootskin
CursorXP: .CurXPTheme
DesktopX Object: .dxpack
DesktopX Theme: .dxtheme
IconPackager: .ip
Logons: .logonxp
Progress Anims: .wba
Toolbar Icons: .wba
WindowBlinds: .wba
To the best of my knowledge, these are the only ones that have been affected. Please post if I have missed any, or if you have questions.
(admins, could this please be a sticky post?)