video card help

If you have a motherboard that has onboard video you do not need a video card.

But people say you sould always buy a video card for the system and not use the onboard ones.

Why?

 

http://www.ehow.com/info_12080107_onboard-graphics-vs-video-card-expansion-benefits.html

 

In the early days of onboard videos, there was a huge performance hit on the entire system due to the facts that the system was using some of the same ram you use for Windows (shared memory), the system MUST redraw that screen 60+ times per second, and could not be running any software during the time the graphics chip was refreshing the screen.
My base system (the lowest I will reccomend) is one which will play a full screen YouTube video without dropping frames or audio and that threshhold was crossed with the Intel 865 chipset (circa 2004).
Any system newer than 2008 has massive improvements above that threshhold and, for most people, an addon video card is just something else to break.
On the other hand, if you want to play serious games, an addon graphics card can be much faster at drawing the scenes than the onboard video; though, please note that the addon often doesn't do any better for normal use.