How can I change or add OEM logo and information on my computer?

By default, the General tab (right-click My Computer, or double-click System in Control Panel, or press the ÿ + BREAK keys on your keyboard) contains information on the Windows version, processor, memory, registered user and registration identity.
Optional items include the manufacturer and model, a small picture, and a button leading to a separate page of support information.

The information is not held in the registry, but in an old-style .INI file, which can be created in any plain-text editor including Windows Notepad.
This file can have two sections:

1.    The first section, has a section header called [General], and within that section -  two entries:
·    Manufacturer=
·    Model=
2.    The second section, headed [Support Information], is optional, but if present adds a button with that label to the page. The entries after that heading should be in the form:
·    Line1=
·    Line2=
·    Line3=
                                                                           
And so on. The limit on the number and length of lines seems limited only by the 64 KB general limit on .INI files.
The file should be saved in the %systemroot%\system folder (for Windows 98/ME computers) or in %systemroot%\system32 folder (for W2K/XP/2003 computers) as OEMINFO.INI.
The picture is a 256-colour-Windows bitmap (.BMP) file.
Microsoft states that the size should be 96 pixels square when using small fonts in Display Property settings, or 120 square with large fonts.
The file should be saved in the %systemroot%\system folder (for Windows 98/ME computers) or in %systemroot%\system32 folder (for W2K/XP/2003 computers) as OEMLOGO.BMP.
No other entry in the .INI file is required, but the latter must exist and have a populated [General] section for the bitmap to be visible in Display Properties.
No reboot is necessary in order for the hack to take place. Press the ÿ +BREAK keys and see for yourself.
For example, using this OEMINFO.INI file:

And this OEMLOGO.BMP picture:

                                                                    
have resulted in this effect:
                   

Pressing the Support Information button will show this text: