If you are really new to Do It Your self, you should start by doing an update on a used computer. Good brand name used computers are with a good warranty for a fraction of the new cost. Most, maybe all, have really wimpy graphics. Getting a good graphics card can do a lot to improve the visual performance of a stock computer.
Notice most low-cast PCs from the big names use only the built-in graphics. The built-in graphics is always wimpy.
So I would say look around for a good used computer that does not have a good graphics card. Then upgrade it to a good graphic card. Good used PCIe video cards sell for about $20 on eBay.
In other words, pick a project withing you abilities and experience and then move on. Otherwise if you take on something too hard, you will become very faint of heart. You don't want that to happen.
