The easiest way i know to straighten wire is the way the ceiling fixers do which is
before you cut it to size fasten one end to a fence post or somthing simular unroll
about 20 yards then fasten it to a old drill electric or battery pull it tight and give
it about 30/40 revs make sure you keep plenty of tension on the wire
then let the drill back wind between 5 to 10 revs then cut it of the drill
PLEASE be carefull as it might still spin back a little when you cut it
you should have a length of straight wire ready to be cut into what ever length
you want
atb stu