An AGP card is a graphics or display card and will allow output to a monitor. A LAN card is a Network Interface Card which allows a computer to communicate over a network, either wired or wireless.
It can be checked easily. You can just search someones LAN card as simple as 123 like some hackers can easily find it in a few seconds.Addition: If you need a LAN card to be checked you need to run...
You can look on the back of the computer to see if there is an RJ-45 jack. This is where you would plug in an ethernet cable. It looks like the telephone jack only slightly larger.
Or, right click...