Memory dump program

I am trying to locate a program to do a complete memory dump of the
physical memory to a file so that I can examine the contents of the
memory forensically. Is there a program that anyone has written or
can write that can complete this task. Ultimately I would want to
dump the contents of the physical memory to a file on a removable
volume, like a usb drive. I have the tools to do this in XP, but not
in VISTA. Any help is appreciated. Thanks
.