Which one should i upgrade first?

My brother recently bought a PC(very cheap though), it's nothing spectacular but at least is slightly beter than my previous 9 years old pc. So i asked a bold question to my friend to lend me his Crysis Warhead.

So i have already installed the game. The game automatically set the optimal settings to minimum for every options. It ran smoothly, so i decided to upped a few settings(Volumetric Effect, Water Quality, and Shadow Effect) to Normal and the game's framerate started dropping alot. I expected this already so i wan't surprised.

Now, i am totally oblivious to PC hardware stuff. Do i need to upgrade the GPU and/or CPU to be able to play on higher settings? What about other stuff? And anyone tried buying the stuff through eBay? Is it reliable? Cheaper?

Thanks for taking the time to read. Help will be greatly appreciated.

we'll need to know system specs

Pentium(R) Dual-Core CPU

E5200 @ 2.50 GHz

1.66GHz, 2.00 GB of RAM

NVIDIA GeForce 8400 GS

That is all the information i could get based on my friend;s instruction. Did i missed out on anything?

Regarding the 2.50 GHz and 1.6 GHz, which one is the processor speed?

Your processor runs at 2.5GHz. Your friend may have meant that your RAM's max speed is 1066MHz. Anyway, upgrade your graphics card first. What kind of PSU do you have?-GeordiLaForge-

Ok i opened the side casing and it revealed the following stuff(hope it helps):

10A 250 VAC

Brand: Power Logic Sonic Gear

450W Max/Peak power and 230W Real/Raw power. (I am confuse about this part)

Ok i opened the side casing and it revealed the following stuff(hope it helps):

10A 250 VAC

Brand: Power Logic Sonic Gear

450W Max/Peak power and 230W Real/Raw power. (I am confuse about this part)

fearino

There is a table graph.

Max DC Output: Voltage | Current | Frequency

230V | 5A | 50 Hz

Orange| Red | Yellow | Blue | Purple | Grey

+3.3V | +5V | 12V | -12V | 5Vsb | P/G

15A | 22A | 12A | 0.5A | 2A | OK

That's about it. I can't find any other info on it. Hope you understand it

Well upgrade your RAM to at least 3 and upgrade your gpu to a ATI 4850 or a gtx 260 but you have 2 have a good power supply, check if your motherboard supports quads and core 2 duos maybe you can upgrade your cpu as well :D.