Which one of the two cards should I get?
ATI Radeon 4830
Nvidia Geforce 9800gt
I am looking for a graphics card that will last a while and am willing to go sli or crossire later down the road. I play mostly FPS games and some actions: Assassins Creed, Bioshock, Crysis Warhead, Gears of War, Tomb Raider Underworld.
Is there another option worth the extra money?
Just depends on what you want. Since they are both pretty close I'd say it comes down to if you want a crossfire or an sli motherboard. Generally I like the crossfire boards better for both AMD and Intel. If you already have a crossfire or SLi motherboard then you may as well base your choice on that.
any of the stated cards are good, but like someone else stated it depends on your mobo. if you have sli mobo then the 9800GT is you choice. also a 4850 is faster than the 9800GT so maybe waiting a little longer will suit you better for the future. 4850 > 4830 = 9800GT. i would wait if at all possible.