If you have a 20a circuit it probably doesn't matter. The HP will be the same
either way, the only difference is it pulls twice the current at 120v. There
may be some I2R advantages in a shop with full time operators but for the
occasional use, home woodworkers it would take 100 years to get your money
back.
If you only have a 15a with something else on it the saw may cause some
nuisance tripping. At that point the rewire might be worth looking into. Get
the Sears owners guide and follow their directions about the wiring of the
motor and the proper plug you should attach. Make your 240v circuit match. I am
guessing they ask for a NEMA 6-15 plug, the one with 2 prongs going straight
across and a 15a circuit. The code would allow you to use the combo (sideways T
slot) receptacle and a 20a circuit. Just be sure you get the 240v model if you
are on a 240v circuit.
The bottom line on all of this is to follow the manufacturers directions on
line cords, plugs and branch circuit requirements. Sears certainly has this
book on their web site.