Gotta be at the lower end of medium for me. This is an excellent site that explains why if you're cooking it well done, you're doing it wrong:
http://www.amazingribs.com/tips_and_...t_science.html
And a fantastic temperature guide:
http://www.amazingribs.com/tips_and_...ure_guide.html
That site is excellent, since I've read it and started cooking with thermometers, everything I've made is so much better. That site has actually ruined eating steak out at restaurants for me. :p