I agree with Richard. You may have to try to install a different driver.
I suggest to find another distro. Ubuntu is based on Debian. There are many distros based on Debian. There are many distros based on Ubuntu.
Ubuntu does not ship with any propitiatory software. To get some proprietary drivers (and codecs) you must plug your computer into the internet during install. This does not guarantee that all will work. Strange thing does sometimes happen.
There are distros that will work better out of the box.
Mint
PCLinuxOS (in my opinion the best out of the box)
Kwheezy
Pinguy OS
Zorin OS (although why have a GNU/Linux OS that looks like Winblows)
Added:
If your computer is that old, I recomend a distro for old or slow computers. Although Ubuntu will install on something as old as a Pentium 4, it is too slow to be usable (to me anyway).
For old or slow computers, have a look at:
LegacyOS (based on puppy and is really fast for an old P4 machine)
antiX
wattOS
SliTaz
Swift (ugly though)