CIsland:
I am pretty sure that the 637 only comes with a 1-7/8" (nominally 2") barrel. Check out the Concealed Carry forum, too, for threads about 637's, 642's, 638's, etc. - the family of fine snubbies.
Bud's has a good deal going now (or was it through the end of 2010?) and Gunbroker may have a few up for sale at this time.
I have a 640 (the fat sibling of the 637) and I think it is the finest little snubby around but that's just my opinion. You won't go wrong with a 637. The only thing to watch out for is the hammer when carrying concealed. A 642 does not have an exposed hammer so give it a lookover before you decide.
HTH,
Chris