Okay, you've won more than half the battle.
Now, after downloading 64bit Ubuntu 12.04 or 13.04, whichever it is, BURN it to a disk.
1. Boot with Ubuntu 64bit and choose "Try Ubuntu". Wait until you have working desktop.
2.0. From desktop open and run 'GParted' , the disk partition management utility.
2.1. Delete ALL partitions by right clicking on a partition and select 'Delete'. Then you 'Apply' the changes. See the screenshots.
2.2. Recreate Partition Table. Click on 'Device' and select 'create new partition table' and choose GPT from 'Advanced Options'.
2.3. Create FIRST partition of about 250MiB and format it as FAT32 and put a "Boot Flag" on it.
2.4. Create 20-25GB partition and format it as ext4.
2.5. Create 20-25GB partition and format it as ext4.
2.6. Create 4GB SWAP partition.
2.7 Create RemainingGB partition and format it as ext4.
2.8. Apply changes
-dev-sdb - GParted_014.png -dev-sdb - GParted_015.png -dev-sdb - GParted_016.png
3.0. Exit GParted and Restart your computer.
4.0. Boot with Ubuntu disk in UEFI mode, if there is an option to do so, and choose 'Install Ubuntu'.
5.0. At the appropriate Screen you will be as how you want to install Ubuntu, choose "Something Else".
6.0. In the following screen select your first 20-25GB partition (Not the first 250MiB partition) then hit 'Change' and choose "/" as mountpoint.
6.1. Now select the 'RemainingGB' partition, hit 'change' and choose "/home" as mountpoint. If you don't want separate /home and use instead a plain partition to store your DATA then ignore this (6.1) step.
6.2. Below, on the same screen, you will see where is Grub being installed, by default it will be installed on /dev/sda. That is good enough for us. If it doesn't say /dev/sda then change it to /dev/sda.
6.3. "Continue" with installation and "Install Now"
7.0. When the installation is complete, as instructed by the installer, REBOOT.
Ubuntu should be able to boot from HDD now. In case there is an issue booting Ubuntu:
1. Boot from Ubuntu install disk and "Try Ubuntu". Once the desktop is ready Connect to Internet, then open Terminal (ctrl+alt+T) and run following commands one after another:
With these commands we are installing BOOT REPAIR utility on Ubuntu Install Disk to repair our boot. More help with Boot Repair can be found HERE.
sudo add-apt-repository ppa:yannubuntu/boot-repair && sudo apt-get update
sudo apt-get install -y boot-repair && (sudo boot-repair &)
2. 'Boot Repair' will run and search for problems, then it will display "Recommended repair", just click on it. That should fix your boot issues. Reboot to check.