The extra power etc. is strictly a guy thing, get her the inspiron and save the money. I know my wife would never be able to tap into the power of the XPS or care if she could, anything that she would want to run on the inspiron will still run possibly just not up to our standards.

Jason
M80 v2
VP160 v3
QS8 v2
PB13 Ultra
Denon 3808
Samsung 85" Q70