It's not really something you need jQuery to do. There is a very simple plain old javascript method for doing this:
window.open('http://www.google.com','GoogleWindow', 'width=800, height=600');
That's it.
The first arg is the url, the second is the name of the window, this should be specified because IE will throw a fit about trying to use window.opener
later if there was no window name specified (just a little FYI), and the last two params are width/height.
EDIT: Full specification can be found in the link mmmshuddup provided.