I notice most $500 PC from Dell, HP, Acer, and other big names have the same, or very similar computer parts, and the CPU speeds are similar, amount of RAM, operating system, and video card are very similar with slight differences like slightly faster CPU, a little bit more RAM, and some more hard drive space.
Would I notice much of a performance or reliability difference buying a new $500 Dell vs a $500 HP, or other similarly price branded computer from a store?
Would the slight speed difference in these two computers improve my everyday tasks like watching video, listening to music, burning CDs, web browsing and office task.
I highly highly recommend building yourself the desktop instead of buying something from Dell/Asus/HP/etc. You'll get soooo much more value.
It's super easy once you have your list of compatible and needed parts. It's basically plug and play. There's no soldering or anything fancy. 9 times out of 10 you just plug the component into the motherboard and connect a cable to the power supply.
I can walk you through building the desktop if you elect that method.