I 5 boxed Vanilla/BC/WoTLK with less hardware than that and sometimes with bad cooling (on a laptop when traveling). The biggest thing I found to make it bearable was using ISboxer to throttle the background windows FPS way down. I may have still had heat issues on my laptop and I may have also used MSI Afterburner (if I recall correctly) to make the background clients even less taxing.

If you run into performance or heat issues I would look at one or both of those tools.