I have a 2gig 2.0ghz MB and when I got it I timed the boot and it took 25 seconds. So no, I don't think the extra ram will boot you faster. It doesn't need 1gb to boot, it for sure doesn't need 2gb.
If you are looking for a faster boot time when I'd do get a flash hard drive or something crazy like that. That may help a couple of seconds. 5 seconds at the most I'd say. It is completely not worth it.
Do you really need a couple of extra seconds in your life?
PLUS! Why the heck are you booting anyway? Why are you turning it off? WTF?!?! Don't, it will wake from sleep faster than 20 seconds so that will save you your time there! I never turn my MB off. The only time it goes off is when I have to reboot to install something. Sometimes if I'm rebooting to install and then I'm not going to use it for a while I'll just leave it off, just because. Unless you aren't going to use your MB for more than a couple of days then DON'T TURN IT OFF!!!
The Stig