Yeah, in reviewing what I wrote, I could have been a little less obtuse.
I've been carrying a 12.1"-screened 2.5lb computer for the last four years (Latitude X1), and think it's about time to go with something new that can actually do the things I'd like it to. However, obviously, the 15" (which I think I'll choose over the 13" purely for screen real estate) will be a big change in pounds carried, and I was wondering if there was a weight savings in going with the integrated graphics.
Since I'm pretty sure I'm not deserving of the discrete graphics card and probably don't need it, but can afford it, I was trying to decide on whether it's worth the weight to have the extra power. I didn't know whether it was like a card in a desktop with its own heat sink, etc. - where the weight might make a difference and help sway my decision one way or the other. Plus, people have been talking about the two fans in the 15" versus one in the 13", and I haven't seen conclusive evidence as to how many fans the the base 15" has. Obviously, 20 grams isn't going to make enough difference to sway my decision!