I had typed a reply last night, thought I hit post to it..........
I looked at all 3 and was going to suggest the same as you have chosen
all 3 look to have nearly the same components but the gateway has a much better cpu.........
, if it wasn't for the processor difference, I would go with the DELL had it had the i5........ I have had a lot better service out of the Dell laptops over the Sony VIAO's or the HP's or the IBM/lenevo ThinkPads
I have never had a Gateway PC or even used one or fiddled with one......
I am sure she will like it though......
cheers
TC