well, a bigger hard drive will allow you to store more data on your computer, ie. music and movies. RAM will allow the computer to run faster, like when opening programs and using programs like garage band and photoshop. 1 gig of ram is more than enough for MOST people, but if your going to be using memory intensive programs, it would be a good idea to go with 2 gigs (maxed out). as far as hard drive size, if your into multimedia, (pictures music and movies) i would go with the big hard drive which is 160gb. they also have a 200 gb but it is only a 4200 rpm hard drive, which is fine in most cases but the 160 gb with faster rpm will be faster. i hope this kind of helps. also, you might want to do a search...