Windows XP checks by default for network folders and printers.
This tweak is useful when your home environment does not
deal with network folders or network printers.It can increase
the explorer performance seriously.To disable the search for
network folders and network printers add the keys below :

- HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows
\CurrentVersion\Explorer\RemoteComputer\NameSpace
>>  \{2227A280-3AEA-1069-A2DE-08002B30309D}\  <<

- HKEY_CURRENT_USER\Software\Microsoft\Windows
\CurrentVersion\Explorer\Advanced\

Add here in the right pane the entry :
>>  NoNetCrawling (as REG_DWORD [DWord Value] )  <<

- HKEY_USERS\.DEFAULT\Microsoft\Windows
\CurrentVersion\Explorer\Advanced\

Add here in the right pane the entry :
>>  NoNetCrawling (as REG_DWORD [DWord Value] )  <<

Doubleclick each entry and set it's value to 1.

Restart your computer!