XPS 9100 Video Card Upgrade

Hello,

I have a XPS 9100 desk top where i want to upgrade my video card  I currently have

System hardware:

CPU: Intel Core i7 cpu 930 @ 2.80 ghz

Memory: 12gb

Motherboard: 05DN3X intel ICH10R

Videocard: Nividia GTS 450

                    PCI Express x16

                   video memory 1.5gb

I want to upgrade to maximum video card but dont know how to look it up or find what my system would support. Im playing BF4 and it keeps saying system video card is not enough.

Can somebody please help me and advice me what to get or how to proceed

Thanks