My current system has treated me well and if I didn't come across a game I couldn't play I wouldn't consider upgrading just yet. I have Unreal Tournament 3 and realized, after looking at the back of the box, the minimum graphics card is a geforce6. I have a GeForce4 Ti4600 and it works just fine with the games I have.
My system is a P4 2.4GHz, 1 GB Ram (PC 2100). I only have AGP video and all the new cards are PCIe. It seems that even though prices have come down considerably, you're still gonna end up paying around $1500 for a good system. Of course, I could just get a new mobo, cpu, ram and a case, but it seems like it will still be a pretty penny.
Any ideas? New system, upgrade current system, don't play new game? hehe