Upgrade to Win7 64 Ultimate
MacBook Pro 15”
Both systems have:
4GB DDR3 SDRAM
Glossy 15” WLED Display
Y550 with the cheap Intel graphics or the NVIDIA?
You do get more overall with a Mac, but you pay more. One of the biggest things is the unibody case, machined out of a single piece of aluminum. It's extremely strong and rigid while being lighter. You really have to handle one to appreciate it. It's so small you twist it hard and expect some flex, some creaking like you normally get with small notebooks, but you get nothing.
Personally, it's the light engineering touches that get me on the Mac, stuff I never would have thought of had it not been pointed out to me. For example, see that power indicator light? There's no point to it when it's not on, right? You really don't need to be seeing that LED when it's not on. Its only function, the only reason for it to be seen, is when it's on. So Apple laser-drilled tiny, almost invisible holes in the case and put the LED behind that. You can't even see it's there unless it's on.
These design details exist throughout the Mac, the tiniest detail has been sweated over by the design team for days, multiple models made until they got it just right. This isn't design for design's sake or to make it look cool, it's design for usability and functionality combined with just the right materials.
The differences in operating system used to be a big one between the two, with OS X being far better than XP or Vista. Now, not quite as much. I've used Win 7 since RC1, and OS X Snow Leopard is my daily OS. Win 7 is definitely not enough to make me switch back to a PC. You also probably won't be using power-sucking anti-virus, etc., with the Mac, effectively making the Mac a bit faster.
So, the basic question is whether all the advantages of the Mac are worth the money.
I left this out because it really doesn’t matter to the computer itself, but the Mac is also more environmentally friendly, from the less toxic materials in it, to the recyclable alunimum case, to the better packaging. It’s a personal decision for you and your daughter as to whether that matters or is worth any money.