I've had a similar problem with an old desktop of mine, and I went through the most convoluted meathod to install Linux on it.
Requirements:
Another computer with a very large hard drive.
Network connection between the two.
Internet.
Patience. (Copying a hard drive takes many hours.)
Note: These are very crude instructions; you will need to tweek the instructions to fit your need. Don't hold me responsible if you f**k something up. This is just something I used which might be helpful to you.
1) Use the unetbootin "frugal install" mode to install install the iso temporarily to your hard drive.
2) Install an ssh server in the live environment.
3) Copy the hard drive to an image on another comuter running Linux:
Code:
ssh ip.address.of.computer 'dd if=/dev/sda' | dd of=./image.raw
4) Import the hard drive image to your favorite virtualization software, install within Virtual Machine
5) Copy back hard drive image back to original computer:
Code:
dd if=./image.raw | ssh ip.address.of.computer 'dd of=/dev/sda'
6) Reboot.