thanks very much, i'll read that now
Is it true that if I install OTA 2.2 without rooting, I can use underclocking programs, and Apps2SD?
Yes you can underclock with the OTA but the perflock isn't unlocked, so you have to apply the underclock after each boot up of the phone.
APS2SD, yes you'll be able to use the FroYo built in AP2SD but it's a poor way of doing it.