Need some advice

I am considering buying a mac and need a little advice. I will be using for the internet but mainly video editing. I have a sony HDR-HC3 and will be just doing little projects like weddings and maybe some short movies. I am in college and cant really afford a powermac so i have decided to go with a refurbished model, possibly a 17 inch imac. What i am curious about is rather i should go ahead and order one or wait for the core 2 duo to pop up on the refurbished market. Also what kind of ram will i need to be doing editing.....my camera shoots in HD and i know that requires quite a bit.
thanks for the help

Core 2 will boost speed while encoding video 20-30%. Why not buy new and use your student discount. Also up-size the memory to 2GB will help.