A new motherboard will cost any where from $50+ then only thing with that is if you get a new motherboard then your probably going to have to get a new CPU also. What kind of CPU do you have maybe I can find a motherboard that will work with it that also has a PCIe x16 2.0 slot. To tell you the truth you would probably come out better buying a whole new computer because after buying PSU,MOBO,CPU,GPU then you have basically bought everything but case,HDD,ODD. I'm pretty sure best buy will put everything in for you but it won't be cheap. Call around to some of you local computer shop and ask them about it. Before you do any thing you should give DELL a call and ask them if your computer will support a PCI express x16 2.0 graphics card. You don't won't to go through all this trouble unless your absolutely sure you have to,