Removing the Shared Documents folders from My Computer can be done without editing the registry on Windows XP Professional.

1. Go the the Start menu, and click on Run.
2. Type gpedit.msc
3. Now go to User Configuration, Administrative Templates, Windows Components, and click on Windows Explorer.
4. In here, you'll see the option Remove Shared Documents from My Computer. Double click on that, tick Enabled, and click OK. And that's all.

Windows XP Home doesn't come with the Group Policy Editor (gpedit.msc), so a registry tweak is inevitable.  This also works on XP Pro.

1) Open Regedit
2) Navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Policies\Explorer
3) Right-click in the white area in the right pane, select New and pick "DWORD Value"
4) Name it NoSharedDocuments
5) Give it a value of 1
6) Reboot (or log off and log back in)