If you've got the space, I recommend a desktop. Years ago I bought a desktop computer and have under $1k in it (nice big monitor, added hard drives, upgraded RAM, upgraded video card) and it has been awesome. Its nice having an extra TB already in the computer for photos. Just save em to that hard drive, no externals, no worrying about slowing down the computer, it just works.
Nice 19" monitor is clutch as well.
Laptops, x-whatever on IBM products. They work very well and if taken care of, last a very long time. I've had good luck with HP, but apparently I'm the only person who has so take that into consideration.
I say, try to get as much RAM as possible, a fast, big hard drive and a good video card. When I was building computers, I noticed those two things make all the difference in the world. Unfortunately I am unable to advise you on these since I haven't looked into computers in years. My current fleet has been going great.
Photos, especially shooting in RAW, will eat through 200GB quick.
Lastly, with "older" computers, you gotta be reasonable with them when photo editing. My desktop which is of 07 vintage can handle 8 photos + pandora + gchat fairly well. It DOES NOT handle 12 photos + 12 videos off of youtube at 1080p at the same time. So if possible, remind her of this.