So as the title states I am planning to use Linux on my new desktop setup and I was just wondering what version of Linux I should get and all the things I need to get Halo CE to run with absolutely no issues.

I haven't used Linux in a while, I am a Windows guy myself. But a while ago I did use Ubuntu, and I recall there being a add on called "Wine" that will run Windows programs. I can't guarantee anything, just something you should look into.

Wine isn't compitable with Halo CE, Try getting a virtual machine
I use this one http://www.vmware.com/nl/products/workstation on windows a lot.

If you have any intention of gaming, just don't use Linux. You can get by with OSX by emulating Windows, but Linux is just bad for anything media-related. The selection of titles that run natively is miniscule and going beyond that requires hacky methods (ala the aforementioned WINE) that don't work at least 60% of the time. Made up percentages ftw, but seriously, look at their criteria for 'compatible'. Just getting the thing to run, bugs etc be damned. I think that's very telling.

I used solely Ubuntu for a year and a half; don't make the mistake I did expecting it to be open sauce windows. Switched back to 7 and never looking back.

This will help you:
http://www.modacity.net/forums/showthread.php?17146-Halo-on-Linux-The-Ultimate-Guide