Are you just looking for a boost when playing videos or are you trying to videogame? A low end video card can work in this PC without modification, but you aren't going to be able to upgrade this older PC to a level that will do well with modern games.
In order to play modern games you would need to upgrade both the video card and power supply -- which I do not really think is worth it on this old emachine unless you are planning to start building your own PCs and using the parts over.
I just need one for a specific game and i got a list of ones that will work with the game but idk which one will work it said the ATI RADEON HD 2400 XT ia aupported idc if its old or not as long as it makes the game work ok with no lag or anything