Select "move window" from Win8 desktop taskbar
You're probably not going to be able to make it act exactly like it did in XP, at least not without hacking/replacing Explorer.exe.
Having said that, in Windows 7/8 you can hold the Shift key when you right-click the icon on the taskbar and you should get the context menu you're looking for (the one with Move, Restore, Size, Close, etc.)