Aperture or Lightroom for Macbook Pro?

I'll look into the memory upgrade.  I need to do a little more reading, but it seems like something like this is all I would need?  That and a small phillips screwdriver to open the casing?

http://www.amazon.com/gp/product/B001PS9UKW/ref=ox_sc_act_title_2?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

I haven't used iPhoto much but I expect Aperture will be a simpler UI just be being Apple