HEWLETT PACKARD HP Pavilion Desktop Computer (AMD A10-5700/ 2TB HDD/ 12GB RAM/ Windows 8) - English - Refurbished - 429.99 + tax (Futureshop)
Or would i be better off getting one custom built, and with which video card/processor, etc? (I am not sure of this stuff since i've never made my own or had a custom pc made before.. my old desktop was a 2003 Compaq Evo d510 XD)
If you do not want to build a computer. then I'd say the Asus M11BB Desktop is best. The Gateway SX2185 Desktop lacks in the graphics card. The HP Pavilion Slimline 400 Desktop has a lackluster CPU and the HP Pavilion Desktop has way more HDD space then you will probably need. Your best bet is to build your own computer. If you don't wanna build a computer then the Asus M11BB looks like it would be the best.
If you wanna learn how to build a computer watch this video: (You do not have to use the same parts as him)
I would be cautious with refurbished products. They are good most of the time but you never know. Those aren't even good prices for being refurbished. The last 2 are what you'd want but a new one would cost $500 (and could cost around $400 if you build it).