1) am I crazy? (specifically pertaining to trying Linux)
Most certainly!
2) Can I go Linux with my rig? ** Rig parts listed below
Almost any PC is capable of having Linux installed on it.
3) Is it too late? I already installed Windows 7.
Nope. Even after installing Windows7, you can still start over. IIRC, the Ubuntu installer makes this very easy, and will guide you through it.
4) I am not a big fan of Windows, have been using Mac for a long time and although I used to know my way around windows, that was about 10 years ago, so I am pretty much starting from scratch either way.... so should I just put that effort into learning and setting up Linux?
I've used Windows, Mac, and Linux over the past 8 years. Windows has more support, Mac is fine if you don't touch it, but you can do almost ANYTHING with Linux. Once you start learning how to set things up how you need them, you just can't go back.
5) If I go Linux, a) is Xubuntu the way to do it and b) is it tremendously more involved than downloading Xubuntu, setting that as first boot and rebooting and starting from scratch at that point?
I would recommend the standard Xubuntu, or Lubuntu if you're looking for a lightweight system. Download the .iso, burn it to a disk, boot off the disk, and run through the automated installer.
6) Do I need to uninstall Windows? I have read about running them side by side, will that work?
You can run them side by side, with a dual-boot option on startup. Or you can just replace Windows. I would recommend the former, as you never know.
7) Am I crazy?
As I said before, once you get your miner all set up and running beautifully, you won't want to switch back to Windows. It just won't have the same features.
A) Give advice or answer questions.
There are plenty of guides and tutorials here on the forums. If that doesn't answer your question, google the shit out of it. You can learn a lot if you know where to look.
B) Predict my outcome......
I predict that there will be several points where you achieve success and go "Yes! Everything is working, so lets mine!". Then something else will catch your eye, and you will go "Hmm, I would really love to add the miner.php for remote monitoring..." or "I could really use an email alert if this thing goes offline for whatever reason...".
Have fun, and Good Luck!