I won't be much help since my laptop has 4GB RAM, a HD 5650 and a triple core @ 2.1ghz
which is weaker than your wife's rig.
I also don't play at 1920x1080 (except when I play on the tv)
I play at 1600x900 and I don't play that particular game so I can't directly help.
Anyway, the best way I could help you is to suggest looking at benchmarks
and YouTube videos of game play of Guild Wars 2 and compare their resolution, graphics card, RAM,
processor against your own and make a sensible judgement.
If you find a video with absent info, you could ask the uploader what system specs they had
at the time of recording and at what resolution, etc.
Good luck.