are you talking about your processor?
that emachines has a 3500 manchester s939, right?
x2 4200 s939 from newegg (65 bucks)
new psu b1g suggested (say, 45 for the fortron)
8800GT 256 or the 3850 graphics. (180 for the 3850)
i'd suggest some ram, too. (hows does ram equal 826?) grab a couple of sticks of (relatively) cheap value ram from new egg and pop them in with what you have (if possible). you should shoot for 2gb, but 1 gb will work if you only have two slots. if you have to use 1gb, i would replace it with a new set.
you're looking at about 300-400 dollars which will be pretty much a gigantic improvement for gaming.
s939 x2's (dual cores) are still very viable and can run new games just fine. and it will last you for quite some time yet.
"nagasama no longer drinks tecate, or streaks out of the night for anything, and he has a fine wife so he has no use for your girlfriend...she is safe..."