no.
you can get quite a good increase in performance with playing with the FSB
what unlocking lets you do it lower the mulitply so that the CPU isnt stressed as much , and letting the MoBo ramp up speed it couldnt do with the CPU and other devices holding it back
and about the wear and tear , that negligable. espeically considering that your XP chip and mine is the same chip, came from the same plant. the only difference is that yours performed better in testing so got the bigger label slapped on it
CPU have a min life of 5 years, i think it would be time for an upgrade in 5 years, wouldnt you ??
just dont go crazy overclocking it by like 1.5 times the speed it is now (like P4 1.6a owners can do)
OH and about unlocking it being worth it, its personal prefernce,
i wasnt going to when i got mine, but the more and more i read bout it i think i might,
in all the forums i read bout unlocking i have yet to read bout one going wrong,
maybe they were too embarassed to post, i know i would