Depending on how efficiently you think charity money can be spent, I'm probably already murdering a child every time I upgrade my computer. So yeah, of course I'll go for this.
I wouldn't try becoming particularly superheroic or supervillainous, I'd just live a pretty chill life, while being immortal, and occasionally kill people. Since forensic technology is likely to advance quite a bit, I'd probably have to get plenty of murders in pretty early to make sure that I have a head start (if I can live 200 years, by age 150 I'll be in a position of power and able to cover things up).
Although I'm not sure if this actually counts as immortality, because, you know, it ends unless you sustain it. Not sure what the technically correct phrase would be, though.
Oh, also, would I die when my time runs out, or would I just become mortal again? (Since I expect science to discover immortality in the next few centuries, even if it's not within my lifetime, and the non-murderey kind would be preferable).