Well there is a big difference between sending her daughter to a school basically forcing her to take something in school and your sister's daughter wanting to take computer courses and learn about it. If she is interested in the subject then she will have no problem excelling, otherwise it is a waste of money to be putting her in school.
My thoughts exactly.
Something that wasn't mentioned was her age. If she's only like ten then thigns can change fast. ANY pre-teen/teenager can use MSword, and play sims and a half-smart person can avoid crap online. But if she's older (late teens) and has the desire to do it, things should be easy.
As a warning, no one is guaranteed to make 60+k a year fresh out of college. Just as an example the average computer or software engineer makes about 50k fresh out of college, and they usually get paid more than a starting IT person at a major company.