Major brand names (HP, Dell, Gateway, Acer, Samsung, Lenovo, ASUS, etc) are the best way to go. I would look at two things when buying a laptop:
1) If there is a problem - where does it get fixed. If there are no local repair shops, the laptop has to be shipped back to the manufacturer, where it could be MIA for 6-8 weeks) - so check to see who does local warranty repair in your area. This also goes for upgrades - see who can do that in your area.
2) Read consumer reviews of the individual laptop models - a good brand name doesn't mean all of their models are top notch. Take the reviews with a grain of salt, as many consumers will purchase something, screw things up, and then blame the manufacturer.
HP and Dell both sell Laptops with bundled software - so you can get Microsoft Office at a discount if that is what she needs (check to see the components she will use like Word, Excel, Power Point, etc - and make sure they have that component included in the bundle).
If Microsoft Office isn't necessary (i.e. Libra Office is a free word processor, spreadsheet and more) - save the bucks there - Office can be as high as $500+ for their professional versions.