Vehicle remote ignition - Some questions.

Okay, after reading around some forums, i apologise for my idiocy..

I found a diagram that someone else has posted, would this be fine to power the arduino?
Regards, Matt.

https://picasaweb.google.com/lh/photo/XfQQ4t57ZujKV4wVzmg48NMTjNZETYmyPJy0liipFm0