It's possible, but I'd advise against it.
In Windows 9x, the logo was just a renamed BMP file in the root of the C
drive. In Windows NT-based operating systems - like Windows XP - the logo
is embedded as a resource in a DLL or an EXE (can't remember which).
There are tools which will allow you to change the logo, but it involves
"patching" the file with a different resource. I know a lot of people do
this successfully, but I personally prefer to keep genuine Microsoft
versions of Microsoft files on my PCs.
Your mileage may vary...
--
Mike Kolitz MCSE 2000
MS-MVP - Windows Setup and Deployment
Remember to check Windows Update often,
and apply the patches marked as Critical!
http://windowsupdate.microsoft.com
Protect your PC!
http://www.microsoft.com/security/protect