I'm not gonna buy a new pc if I can help it, I'd rather just upgrade all the crap inside, so do you know any kinda prices im looking at?
Internal Hard Drive
Well 1-1.5TB usually start from around $130-185
if you want 500GB usually go for around $70-115
RAM (Random Access Memory)
usually cost cheap
System Memory and Storage
Memory is cheap these days. Buy at least 4GB of RAM. Use whatever speed is recommended for your system (DDR2-800, DDR3-1333, etc.)—end of story. For storage, getting a 500GB hard drive should only cost a few extra bucks compared with a standard 320GB one, and will hold many games. You can get a system with one or more solid-state drives (SSD) instead of a spinning SATA hard drive, but they are very expensive on a Gigabyte-per-dollar basis (around $300 for a 256GB SSD versus $60 for a 1TB SATA hard drive). If you're really impatient, the SSD can dramatically decrease loading times and reboot times (seconds vs. minutes), but for now they're not worth the added expense unless you're flush with cash.
Video Card (Graphic Card)
A decent one goes from $76-120 maybe..
Graphics Muscle
Just about every one of the PC reviews on pcmag.com lists integrated graphics as bad for gaming. This is for the most part true, but integrated graphics like Intel HD Graphics 3000 and ATI Radeon HD 6450 can handle limited 3D gaming. These graphic processors (GPUs) are certainly powerful enough to handle most casual games like Diner Dash, Farmville, and even light 3D games like Torchlight, Sims 2/3, and Spore. Getting a single high end GPU like the ATI Radeon HD 6670 or Nvidia GeForce GT 560 Ti is enough to play high end games like Crysis, Lost Planet 2, or the latest graphics masterpiece at moderate screen resolutions (1,280 by 720 in our standard tests).
If you want to max out your 3D performance and likely send your credit card cowering, then you can upgrade to two or three high-end graphics cards like the ATI Radeon HD 6990 (with CrossFireX) or Nvidia GeForce GTX 590 (with SLI). These highest-end graphics card will add over a thousand dollars to your final price, but then again these highest end PCs are the gaming equivalent of a million dollar supercar.
Make sure you buy one of those 24 to 27-inch 120Hz high-resolution 3D-capable monitors to make your multiple GPU system worth it. I'm still unsure about the viability of stereoscopic 3D in the gaming PC market, but you will be prepared if 3D ever takes off. Just be forewarned that stereoscopic 3D usually requires you to use 3D glasses. You may never use the system to its highest potential, and there will be something faster in 6-9 months, but you can tell your friends you have arrived in the upper strata if you buy one.
In my opinion just buy a new CPU eMachine is really old and not really for gaming in my opinion