I am new to this hobby so someone explain the taper designation
on the x1micro mill. the parts list says M2 taper but the
drill chuck says J2, what is the difference, If I get some collets
which ones fit the M2 or the J2 or is there any difference

by the the drill chuck arbor is now out just had to whack the
drawbare a good one and it came out.

M2 is the taper inside the spindle.

J2 is the taper inside the drill chuck.

The drill chuck is held by friction on the small angle J2 taper. To assemble it make sure everything is really clean and dry, insert the taper in the chcuk and give it a good bang with a brass hammer or something softer than steel. It need never come off.

The M2 taper is held in the machine by tightening the drawbar but not too tight, as you now know.

To hold milling cutters you need a set of M2 collets which are a standard item probably from the same place you got your mill.

The "Machinery Handbook", which by the way should be one of the FIRST purchases made by a hobby machinist, explains the various tapers and also gives the industry standard dimensions for same.

http://en.wikipedia.org/wiki/Machine_taper :)