My Computer in XP not only shows your hard drive but other things like camera scanners and Shared Folders too. I find shared folder getting listed there are useless as its one of the most unused folders of Windows. Here is the trick to remove it:

1)  Enter Regedit in the run box [ winkey + R ]  
2)  to the following key:
     HKEY_LOCAL_MACHINE   \   SOFTWARE   \   Microsoft   \   Windows   \   CurrentVersion   \   Explorer   \   My Computer   \ 
     NameSpace   \   DelegateFolders
3) You will find a subkey named {59031a47-3f72-44a7-89c5-5595fe6b30ee}.
4) *If you delete this, all of the Shared Documents folders which is normally grouped by windows under Other Files and 
     Folders , all the shared folder will be gone.

*Please make sure that you make a backup before you delete.

In case you want it back add the key back to the same place and it will appear again. Note, removing from registry does not physically delete them but just removes from listing them under My computer.

You might find more keys under the same. Each will have specific description. Seeing that you will understand what it means and delete if you dont want those too be listed . e.g Scanners and Cameras.