processors for a studio 1555 laptop

hi, i have a studio 1555 laptop 6gb ram 500 hard drive ati 4750 grafix card i have the centrino duo processor t 6500 and i was wondering if i could put either of the next generation processors in to my laptop to help speed it up as it should be quick but i find that there are some tweaks that are needed to be faster i was wondering if an i3, i5 or an i7 would be compatible (straight swap) using all the other gadgets built in it mother board etc. if not what things would i have to change if at all cheers any advice would be greatful thank you