Hello everyone on the Ubuntu forum
I recently installed Ubuntu 12.04 LTS on my Acer 5542G. It worked perfectly, I could do everything great, and I really like the OS. Now, I won't lie, I only came to Ubuntu for the free item in TF2. But, after experiencing it, I quite like how it works, and am interested in learning more about it. I honestly wanted to install it for a while, and the item was the push I needed. So, back to my problem. I went into Ubuntu for the first time, I updated a bunch of stuff from the Update Manager, and I installed Steam. Now, when I opened steam, it asked me to install some drivers for my graphics card (An ATI Mobility Radeon 4570 HD), and I pressed accept, thinking it was a routine driver upgrade. Then, I was asked to reboot, so I did, and that's when the problems started. I was greeted by a blank purple screen when the computer started back up. I let it sit for a good 20 minutes, thinking maybe it was installing the new updates in the background or something, but then I gave up and had to shut it down manually. I really want to get this working, since I want to get to know how to use all this. Any help would be great By the way, if you haven't already figured it out from the forum, this is my first time with Ubuntu, and I have pretty much no knowledge of what to do. The extent of my adventures with Ubuntu was installing the 32 bit libs for Steam to work. (I'm on a 64 bit system. I don't know if this broke it either.)

Now, some stuff which might help:
Processor: AMD Athlon II X2 M300 @ 2 GHz
Graphics: ATI Mobility Radeon 4570 HD
64-bit Ubuntu 12.04 LTS
I'm dual booting it with Windows 7 Home Premium 64-bit
I have 10GB for the /root partition
500MB for the /boot partiton
5GB for swap
and 25GB for the /home partiton