Ok so my gf wants to upgrade her 2GB macbook pro to 4. Now what i'm wondering is, is there already a 2GB stick in there and she needs just one more two or does it come with one so she would need to order two and two. Another question. With a 1GB macbook could i put a two in there and make it have 3GB of ram or would i need to order another two and a one and replace the original. thanks for helping i'm really confused!!