Elements does not offer hardware acceleration, so any card will work that will fit your motherboard
ATI costs less than nVidia (in general) and I would recommend at least 512Meg of memory on the card
The one consideration might be - will Adobe add MPE (Mercury Playback Engine, relying on CUDA) to PrE 10? If they do, then it will be like PrPro CS5, and only benefit from an approved/certified nVidia card.
Considering the price-points of PrE, I rather doubt that MPE will be added, but do not know.
Otherwise, either ATI/AMD, or nVidia will do all that you can do. I would get a current model, from either.