Esther, my husband at a look at the specifics of your new graphics card and rated it an "ok, it'll do."
Keep in mind he's an avid gamer and therefore has to have the best (when I 'allow' new computer purchases)
He said it was about the same as my Mac laptop, which is a year old. I have Ambitions installed on it and everything ran great on medium to high graphics settings in-game until the LN patch. I don't have LN yet but since the patch I've had to turn 2 settings down a notch to maintain the same quality of functioning.
So, all in all, it should be able to handle Sims 3 + EPs. At least that's what I'm told. It might depend on what your in-game graphics are set as.
Hope this helps.