Ofcourse there are various improvements from 10.04 you can see General info here and through here.
For requirements and also improvements refer the Official Ubuntu System Requirements and here too.
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.
You may also try Lubuntu , you can further read about Lubuntu’s requirements from here.