4GB no question between the two.
If I were you though I would throw down the extra 300 and get the 4gb 256GB. For about an extra quarter you're adding 128GB! The worst thing is shelling out 1500 for a machine and then having to use monolingual or xslimmer to try to squeeze out an extra few gigs. With 10GB of pictures and 30GB of music you'll be sitting on about 70GB of space left and that is not including any applications. (You'll probably have 120GB of useable space before an OS and the OS will take 8-10GB). Let's add another 10-15GB for your applications and now we're at closer to 60GB of space left. As opposed to over 160GB of space left. We're talking about 1.875 dollars per gig which is very worth it for SSD space.