Good question! Mine are running fine but the 2010 drivers are seriously lacking when it comes to gaming with today's releases. Mind you, even ATI haven't been able to solve the crossfire issues with Skyrim and that includes the Radeon 6970's.

naryka, bear in mind that if you change the spec of your machine your warranty will be voided unless the components are purchased from Dell and installed by one of their approved techs.

actually i ran ati/amd drivers on my first replacement M17x R2 with dual 5870's never used dell's except when  they asked for troubleshooting reasons  also modified .inf's can be found to optimize the 5870 .. it is very much supported just not by dell  just gotta look around as for xfire i never ran it since games i play didnt really require it (orangebox games, but crysis 2 loved it lol)

anyway as for warranty you can swap whatever you want and it dont void warranty ..  just you need to keeep original parts incase of warranty issue so that dell rules out it isnt your parts causing issue  and ofcourse any damage done while changing said parts is your sole problem*

well my warranty is off anyways, so it doesnt really matter anymore, im just wondering if i could get the new 2gb nvidia card in, instead of the radeon xfire card

Can you point me in the direction of the modified .inf's for 5870's you spoke of please. Crossfire with Skyrim may be impossible for the moment but I would like to see improvement in Assassins Creed and NFS 'The Run'.

as for the card it should work i know there is info  on google that can proove this ...

as for 7League it was  an older driver  over 14 months ago when i had a working R2 LOL   it was from

http://www.laptopvideo2go.com/ at that time