I have found a strange behaviour of my computer, provided that I can run Ubuntu 9.10 on it. But, if I try to run any newer version of Ubuntu, it tries to load the OS for a couple of seconds but then it freezes. The same behaviour appears with new Debian distros and Windows 7, so I guess my hardware is too old for new operating systems. Can I upgrade manually the software that Ubuntu 9.10 uses, like Gnome, Firefox etc.?
You have the Intel DG33BU motherboard with the original 0326 (12/06/2007) BIOS firmware. There have been about 20 new BIOS updates since your original 0326.
The latest version is 0572 (7/15/2009), and is available from http://downloadcenter.intel.com/SearchResult.aspx?lang=eng&ProductFamily=Desktop+Boards&ProductLine=Intel%c2%ae+3+Series+Chipset+Boards&ProductProduct=Intel%c2%ae+Desktop+Board+DG33BU
Give it a go and I believe you will be able to boot and run Ubuntu without a problem.
UPDATE Get the ISO file with the update. Then, burn the ISO into a CD (or use Startup Disk Creator to install to an empty USB stick - not sure if it will work). Then, boot from this ISO.
There is an alternative to use BIOSDISK, a project from Dell. It might be a bit complicated; try first booting from the ISO, once written to a CDROM.