This is an easy trick for windows 9x and I'm sure most of u know it, but if you dont then u can learn it from here.
R u tired of your boring Start up screen? Want to make it cool and funky?
Then try this-
STEP 1- Go to MS Dos and Type
Attrib *.sys
[Press enter\Return]

This will bring this list on the screen-
SHR C:\IO.sys
A SHR C:\logo.sys

On some computers, u may not have the last item on the list. There could be a file called logow.sys or the file could be present in the windows folder. In those cases, you should copy logow.sys to drive c from the windows folder. If u r a newbie and u don't know how 2 do so, then just type the following-

cd windows
[Press enter\Return]
copy logow.sys c:

You can also do this by using drag and drop method or copy, paste. (RMEMEBER, I SAID COPY, PASTE AND NOT CUT, COPY, PASTE) But this method can be insecure because one can easily mess up with the files. So always keep backups of your files.

This file is hidden system file and a read only file. To remove these attributes,
STEP 1- Go to MS DOS
STEP 2- Type the following-
[Press enter\Return]
attrib logo.sys -s -h -r

This command will remove the attributes.

Next Go to MS Paint, open the file and fiddle with it. Save it back in its folder with the same name and extention.

Then set the same attributes by going to MS DOS and typing-
attrib logo.sys +s +r +h

Now exit MS Dos and restart your computer.

Enjoy your new screen.
(There r some softwares which can do the same but there is no fun using somebody else's software and call yourself a computer enthusiast)