Current situation with laptop G/cards

[slugger_2003]

I have been humming and hoeing about what to do...buy new desktop or upgrade laptop. I shall post a thread later with the exact specs of my laptop but for now just want a little info on the latest news (basically because I can't remember the exact specs...)
I currently have a 7900gs in my Dell Inspiron 9400, which cards would be a noticeable upgrade from this and how easy is it to change?