Help and how to install MATE 1.2

[GaryIKILLYOU]

So here is my woe. I've tried installing Ubuntu 12.04, and I don't like the Desktop Environment. So I did a quick Google search and found MATE 1.2 . Everything went great, but for whatever reason it will not install. I've tried the add repo command and everything went ok, but after the apt-get update it gave me a bunch of 404's. I can't install it for whatever reason. I really hate unity, don't like xfce, lxde nor KDE and really just want Gnome 2 back. I wouldn't have this problem because I stuck with 10.04, but as you know 12.04 came out, and I like to keep my system at least moderately up to date.
I've been with linux and tried many distros and usually have had little problems and such, but nothing I couldn't fix with a Google search or forum crawling. I'm absolutely stumped. I have literally no idea where to go. I've tried it with both a 32 and 64 bit 12.04 install as well. I'll post my specs for this machine as well to help out.

Core 2 Quad Q9650
6 GB DDR2 Samsung OEM Memory
Nvidia GeForce 8500GT
320 GB Seagate laptop H.D.D
450 Watt CoolerMaster PSU

 

[Leeky]

Can you post up the contents of your sources.list (located at /etc/apt/sources.list) please, as I'd like to see what you've added to it.

Also, can you post up the full results of apt-get update as well please.

You can add them as code, but using the [ c o d e ] text goes here [ / c o d e ] tags, without the spaces.