Hey guys, I have written this article for the sole purpose of informing you that the Nvidia GeForce FX 5500 will not work in ubuntu with unity. It's better for you to upgrade your system or find a mirror for the old versions of Ubuntu.
If you have decided to download an older version of the Ubuntu operating system. You can download the old releases here. For installing the driver, you can read my post about installing GeForce FX5500 driver in ubuntu.
But if you still want to install the latest ubuntu release, then you need to ready yourself for an upgrade. Yeah, you can still run ubuntu in 512mb ram and atleast 1Ghz of CPU power but with the latest releases of Ubuntu, you will need a slightly better video card for your machine. For a technical reference, please refer here.