Don't be in too much of a rush to get a new card; Empire is not going to be silky smooth unless you buy serious overkill. With that said, your card is pretty much at the low end.. did you scroungs it up from your old PC, by any chance? 
Still, it's above normal minimum requirements, so if you want to hold on to it for half a year and then get an even better new card for less, that's an option.
As for Empire, I find it's finally a good game with 1.6+. VERY good, even. 