GNU/Linux/Free/Open Source friendliness?

<p>Hello all,
I am strongly considering UT Austin for my CS degree, but one thing that is really important to me is not using any proprietary software when possible. Can you make it at UT without using Windows at all? Are the assignments (particularly CS) Linux-friendly? Are there any required online utilities that use non-free software such as Flash? Does the CS department ever work on or contribute to free/open source software?
Thanks for any answers you have.</p>