If you wanted a gaming laptop then I'd recommend Dell Inspiron but the Inspiron series is big, bulky, and expensive.
You definitely don't want to give your sister an 8lb laptop (that's what the Inspiron weighs). If she just does word processing, surfs the web, and takes the laptop to classes then you want one of those thin and lite laptops. However, the thin and lite ones also cost a lot...
The best solution is a Desknote. They are lighter than Dells and have great prices...ECS A901 Intel Celeron 1.1Ghz 128M/14.1/10G/CDROM Desknote notebook computer can be had for 700 bucks from
http://www.sybercom.com/ . the site has a resellerrating of 9.69 which means that they're reliable. This desknote will be cheaper than any dell refurb and will meet your sister's needs. The Desknote weighs only 5lbs compared to the 8lbs of the Inspiron. Look around
www.sybercom.com and I'm pretty sure you can find something which fits your needs. They have a bunch of good deals on low end desknotes on that site...The "Desknotes" are probably better than normal "laptops" for your sister.
hope that helps!