Can you tell me more about performance comparrison between 10.04 and 12.04. Is 12.04 much resource hungry? I have Pentium 4 2.8 GHz, 1.5 GB of RAM and NVidia GeForce FX 5500. Is that enough for smooth Ubuntu 12.04.
While the minimum memory requirement for 32bit is 384 MB, a minimum of 512 MB is needed for the 64bit installation. On systems with only the bare minimum amount of memory, it is also strongly recommended to use the "Install Ubuntu" option as it uses less memory than the full live session.
The Ubuntu 12.04 installation image does not include support for old computers that do not support PAE. If your computer is affected, you can either first install Ubuntu 10.04 or 11.10 and upgrade to 12.04 or you can use the Lubuntu or Xubuntu images. The non-PAE version of the Linux kernel will be dropped completely following the12.04 release.
Ubuntu 12.04 will run fine enough on your posted specifications.