I don’t know what host you use, but when you are running in to trouble with 32 bits VSTi’s crashing or not showing the GUI, be sure to check jBridge’s bit bridge. It’ll cost a small fee but can save you a heap of trouble when working with (older) 32 bit plugs in a 64 bit enviroment.
On a side note, you say you just copy the DLL’s over. I would personally always re-install the plugins on the new OS.
Future version installers of the plugins will find the appropriate plugin paths easier then.