I have an old Asus EEE 1000H with Windows which I don't use (having a newer PC). But I thought it would be interesting to replace the Windows with Ubuntu on the EEE to give me some experience of Linux.
Should I download the latest version or go for an older one?
You shouldn't have any trouble with the latest release of Ubuntu (14.04.1 LTS) on your netbook, but I would recommend picking the 32-bit variant if you have less than 2 GB of RAM. Unlike Windows, Ubuntu's system requirements do not generally increase as newer versions are released. One thing to watch out for is graphics support, as versions of Ubuntu after 12.04 removed support for 2D graphics, but I have only had trouble with this on Pentium 4-era desktop computers.
From the general specifications of your computer that I found online (Intel Atom, 1 GB of RAM, etc.) don't expect a lighting-quick experience, but it should be plenty usable. I have had Ubuntu 12.04 running on an HP netbook of similar specs and was able to play YouTube videos at acceptable quality.
Official Ubuntu system requirements are here, and you can get Ubuntu here.
You can also try a more lightweight distro like Lubuntu, Xubuntu, or Kubuntu if Ubuntu proves too graphically demanding.
