Alright, reading through your Question, I want to recommend one thing. That you do not buy a computer from a store. The reason being, is the concern of quality. When you buy a computer in a box from a store, they tend not to last as long, considering using the same parts over and over again and shipping them to multiple companies quality is lost. So, if you do insist on buying from a store, don't buy a Dell, they are probably the worst brand when mass produced. I recommend buying from a Company Site, like Dell.com, or HP.com.
So, now, onto your computer choices....
From what you see, you'll pretty much just need one of today's "regular" computers. Here are 2 recommendations, 1 will be Dell, and 1 will be HP. Since these are the most inexpensive and well-known brands. Although I will start out saying, I recommend HP before Dell. The specs with 3 stars beside them should be your primary focus for what you need it for.
~Dell~
1. - Dell Inspiron 15R - http://configure.us.dell.com/dellstore/config.aspx?oc=fncwv01b&c=us&l=en&s=dhs&cs=19&model_id=inspiron-15r-n5110
Specs -
- 15.3 LED Backlit Screen
- Intel i3 Processor (2.10GHz)
- 3GB RAM ***
- 320GB (5400RPM) Hard Drive
- Intel HD Graphics ***
~$500~
~HP~
2. - HP G6T Series - http://www.shopping.hp.com/webapp/shopping/computer_can_series.do?storeName=computer_store&category=notebooks&a1=Category&v1=Everyday+computing&series_name=g6t_series&jumpid=in_R329_prodexp/hhoslp/psg/notebooks/Everyday_computing/g6t_series
Specs- (Recommended Upgrades Included)
- 15.6 LED Backlit Screen
- Intel i3 Processor (2.10GHz)
- AMD Radeon HD 6470M Graphics Card (512MB) ***
- 4GB RAM ***
- 320GB (7200RPM) Hard Drive
$550
So these would be my 2 Recommendations. On the HP Laptop, you can use the basic configurations and get that Laptop for $430, although I at least recommend upgrading to the Graphics Card I suggested at least for an extra $50, your total would still be under $500 at $480.
If you plan on Walmart or Radio Shack, look for these Specs in the computer you plan on getting---
- Intel i3 Processor (At Least)
- 3GB RAM (At Least)
- 320GB Hard Drive (5400RPM) At Least
- Intel HD Graphics (At Least) AMD or NVIDIA Card is recommend though for games.
All of this starts at about $400 at cheapest. From there, the price depends on the Brand, and store. I recommend going by Acer, HP, and Dell as your 3 primary computer brands, Dell being the last, the others will last longer.
Hope I Helped!