upgrading my hard drive

hey everyone

i bought a new 13in MBP about a month ago from my local applestore, with the standard 250GB hard drive. however, i've recently been expanding my music and video library exponentially, to the point where I have over 100GB of music. i want to have plenty of space on my computer so i can comfortably store all of the files i want. in hindsight, i would have ordered my MBP online so i could upgrade the hard drive to 500GB for only $99...but anyway...

how can i approach upgrading my hard drive? can the apple store do it? i know nothing about internal computer structure, so i would be hesitant to install a new hard drive myself. also, how would i transfer my files from my old hard drive such that my MBP with the new hard drive would be exactly like my old one just with more space? how much memory should i consider? 500GB seems fine, but it seems that I can pay around $100 for a TB worth of memory...

thanks! sorry for all the questions..

Look at the guides I have done in my sig.

Good luck.