syn

ok...i have a dell xps 720 h2c,running on win xp (home),witch comes with a dual 768mb Nvidia GeForce 8800 GTX graphics card,i also have 4gb of DDR2 ram,recently my graphics card "fried n died",so it needs replacing,have been recomended the Ati hd4870 witch only comes with 512mb ram but the procesor aparently is pretty cool....can anybody advise me weather i can use this card in my p.c. without any problems or should i stick with Nvidia...am unsure and dont want to waste money on a product i may not be able to use.....