In what did you post in the pics this means you have the case, buying the pieces second hand will not give you insurance that those pieces will break(I think you should buy new ones with warranties)
A mother board that supports a dual core or more with DDR2 or 3 support, and PCI Express, minimum a dual core CPU, and a good video card, and a source that will support that board.
I suggest buying those parts with warranties instead of buying then second hand(old parts could break, or are damaged), if the items are old or old models usually cost more then a new model part in the magazine(Ex: SDRAM > DDR1 > DDR2).
If you want lineage 2 to work this are the lowest that I know it works:
Mother board G31M-ES@L(with onboard video, intel G31/G33, card new games will work, lineage 2 will work, big lag in some towns, if you end up in newbie town you will not be able to login, client will crash)
Intel Dual CPU E2140
2GB Ram DDR2
ATI Radeon X1650(in my opinion this is the minimum video card you could use, had no problem with L2 and DC Universe, played the game with medium/high setting).
You could make a PC to work with low specs, with less then 200$