Here is a simple method..
- Download Microsoft_User-Mode_Driver_Framework_Install-v1.0-WinXP from http://go.microsoft.com/fwlink/?LinkId=71641&/umdf.exe and install it in your PC.
- Go to Device manager by right clicking Properties in My Computer. Uninstall drivers of that MTP thing( if it is having yellow exclamation!).
- Reconnect your device i.e your Samsung Galaxy... and you are done after giving your XP a few minutes to install it.