I’m soon to purchase a Dell XPS 420, but am not sure which graphics card i should buy with the personal.

There are two graphics cards to select from.

they are: 512MB ATI Radeon 3870

Single 512MB NVIDIA GeForce 9800GT

It does not cost me extra to select between the two crads, but i want to know that i have the right card 4 playing my games.

The majority of my games use NVIDIA, and only one of my games uses ATI, so if i buy a NVIDIA graphics card will my ATI game be low quality (graphic wise), and if i purchase an ATI crad will my NVIDIA games be low quality?

Which should i buy?

Answer:
in my opinion, you should always go for the nVidia graphics card, as most games will always work, and the ATI games will work, not quite as high quality, but still great, and if you buy the ATI card, your nVidia games will be low quality.
Answer:
I perfer NVIDIA personally. If your games are designed around NVIDIA then its a good idea to go for the GeForce 9800GT. Also I have tried out a GeForce 9800GT and its a quite nice graphics card.
Answer:
It is choice of the price & your own preference!
Answer:
get the 260 or 280 and get them from www.newegg.com they are extreme! but i guess u could go with a 8800 gtx or 9800 gx