Been a while since I last posted but I think I have the problem with Pidgin crashing every so often in Vista 64-bit figured out.  My guess is that it has to do with UAC (User Account Control).  Disable this and it seems like it’s a lot more stable.  I haven’t totally tested this theory yet but I’m going to do some more research on it and see if I can isolate it.  And no, silent mode of UAC doesn’t help matters either.