Supercard

Does anyone know if a Supercard does very well running roms on a NDS ?

Supercard is considered a good card.Read the gbatemp.net review here:
http://gbatemp.net/index.php?showtopic=88932&st=0#entry1184145

Have you considered other choices?

yes, I have considered other choices, but i was wanting something that would play both nds and gba roms.
Do you have another suggestion ?

So you're looking for a slot 2 card then? So that it has on board ram for GBA and can still play NDS roms?Yeah, I would say its the best.I actually have one that can do that.But do to the fact I already had slot 1 cards, I only play GBA roms from it, so I don't know what the speed/possible lag if any NDS roms would do to it.