Logo.sys is the startup logo file, and is located in the root directory of C:\ In windows 95. The file does not exist in Windows 98 or ME, but can be inserted into the root directory of C:\ to change the default startup logo.
Logow.sys and logos.sys (C:\WINDOWS folder) are the two shutdown logos for Windows 95 and 98. they do not exist in, nor can they be inserted into Windows ME.
A simple logo.sys file (without animation) can be created using any paint program. The format must be a 320X400 pixel bitmap at 256 color depth. Logow.sys and Logos.sys are the same format. You simply change the .BMP file extension to .SYS to create a logo file.
There are numerous shareware and freeware programs which can also produce animated startup and shutdown screens. Most shareware websites will have them.