I F.E.A.R. for the worst

So, I reserved a copy of F.E.A.R. a few weeks ago. A couple of days ago the demo came out. So, I downloaded it. Now I have a fairly decent machine.

AMD Athlon 64 3400+
MSI VIA K8T800 chipset K8T Neo-FISR2 mobo
Nvidia GeForce4 Ti 4200 AGP 8X 128MB DDR
1 GB DDR (400) ram

Now, F.E.A.R. runs on the Unreal Engine 3, the same engine that powers Gears of War for the 360, I was expecting to be able to run the demo with medium performance, but NO! I can't even get the damned thing to start. It'll play through the opening movie, and then once it starts my system freezes and I have to CTRL+ALT+DEL to close the demo. GRRRR! It comes out in October and I can't even run the demo. WTF?

So, I've been saving up cash all summer to buy parts to fix my 2ndary computer. However, since F.E.A.R. has put it to my computer I've decided to ditch the 2ndary parts and concentrate on upgrading my primary. I've been looking at getting a new mobo that supports PCI Express and SLI and buying a kick ass new video card, possibly a GeForce 7800 GTX, in hopes that somewhere down the road I could add another of the same caliber for enhanced performance.

I've been looking at the parts, but I have butterflies about buying it all.