[JoshhSmithh]

Hi, I currently own a BlackBerry Pearl 8100 with a Pay As You Go SIM card in it, I will be soon switching to a BlackBerry Curve 8520, will the SIM that is currently in the Pearl work in the Curve?

And by work I mean; I bought a 6 month BB Booster pack from my carrier for this SIM, will the Booster pack still be active if I put the SIM in a different BlackBerry?

[MidnightDraven]

Yes.
You need to login to your BIS account [where you registered/setup email] and use the "Change Device" option.