Someone else replied with these instructions and they worked for me..
Make sure your iPod is hooked up to your computer & turned on.
Click on "Start" and in the search box type "regedit". This will display a program called "Registry Editor". Open it.
Click on the "Edit" tab and select "Find...". Type "Mary" in the search box and click "Find Next". It will bring up a list of everything that has "Mary" in it. (You may have to click on "Find next" under the "Edit" tab in order to find the associated items that have something to do with both "iPod" and "Mary".) What you need to pay attention to is not the NAME, but the DATA column. For me, the wrong iPod name was listed in 2 places in the data column. The actual names of those 2 items were "FriendlyName" and "Label".
Once you find the associated items that have to do with both the iPod and "Mary", right click on one of them. Select "Modify...". A box will open giving a "Value Name" box and a "Value Data" box. The "Value Data" box should say "Mary's iPod". All you have to do is change it to "Steve's iPod" and click "OK". Repeat the "Modify..." and renaming of the "Value Data" steps for every item that says something about "Mary's iPod".
Close the Registry Editor. Open "my computer" and see that it changed the name of your iPod back to "Steve's iPod".