Originally Posted by: BrokenJeraif i tuned my guitar to C (2 1/2 steps down i think it is) would the lowest C note be middle C (as equal to middle C on a key board)?

The distance between E and a C lower is 4 half-steps, or 2 whole steps:
E (HS) E-flat (HS) D (HS) D-flat (HS) C

The site light487 linked show the ranges of various instruments:
http://members.aol.com/pjay99site/Instrumentranges.htm

It should be pointed out that the image shows the actual pitch of the guitar. It extends down to the E on the first ledger line below the bass clef. In order to place the notes of the guitar entirely on the treble clef, for easier reading, guitar notation is traditionally written an octave higher. So we get this as "middle C" in standard transposed notation:

E |-----|
B |-----|
G |-----|
D |-----|
A |--3--|
E |-----|

The result of this is that "middle C" on a piano played as it actually sounds on the guitar is the note at the first fret of the B string:

E |-----|
B |--1--|
G |-----|
D |-----|
A |-----|
E |-----|