Well without the information it is hard to if not impossible to help you resolve this issue.

On-board video graphics has been around for quite some time and normally there can be an add-on card installed to replace the failing on-board one. The problem is that there are different formats (versions)....meaning there is three different ways to attach the replacement to the motherboard.. PCI or AGP or pci-E.

they all have have their own special mounting sockets for installing them to the motherboard.

The newest protocol for graphics is the pci-E.
AGP would be the next logical choice but they come in various modes of 1,2,4,or 8 with each progressive mode better than the one before...problem being that they will all fit the same socket for installation purposes but they may not all run on your computer....totally dependent on your motherboard and what BIOS is available or installed.

The other choice of PCI would be the most logical choice but the number of available slots that are on your motherboard determines as to the advisability of installing one
example: say that your motherboard has 3 PCI slots and they are all being used by other cards...you would have to make a decision
as to what could be illiminated...and then is it really worthwhile now...have video but lose the sound card....or have video and sound but lose the ability to connect to the internet...get the picture.

There are applications that are available to determine what hardware is installed or what motherboard brand you have...but without the abillity to see then they are useless.

Without the required information I am going to have to state that you should take the computer to some qualified shop or friend that can determine the needed information and inform you on the feasabillity of what it is that you need to do...I say this because it might be best if you just buy a new motherboard combo with on-board video and sound and LAN add a bit of new ram and have a better computer than just replacing the video card.

Video cards can be found (new) online for about $50 give or take some...
combo motherboard units( motherboard and CPU) with built in video and other things can be got for just a few dollars more than that...Add ram and you have a fully upgradeable computer again for about $100 in parts....

One must be able to determine if the purchases will fit of course and then that would be determined only by physically examining and measuring the case...etc...