IMHO In-N-Out doesn't hold a candle to Five Guys (and I'm from California and have had In-N-Out about 100 times) but rather than start a war I'll just say In-N-Out is the best west of the Mississippi and Five Guys is the best east of the Mississippi.
Here's the Five Guys page for the one in
West Knoxville. The easiest way to describe the location is that it's just off the 40 at exit 374 in the same parking lot as
Walmart (you can see Walmart from the freeway if you're heading east on the 40) and right across from a Chick-Fil-A.
--Mr. DB