Re: Which Linux distros do you use?
For production/QA/Dev systems at work, it's either RedHat Enterprise....but most likely CentOS (a RedHat Enterprise clone). I grew up and cut my teeth on RedHat. I've gotten certifications in RedHat. All of my books and work documentation that I maintain is based on RedHat.
For home workstation use, it used to be Fedora. And I still use Fedora from time to time...but I've honestly found a happy spot with Ubuntu. I like the long term releases, the multimedia stuff and eye-candy seems to work relatively easily and the ease of adding the restricted nvidia/ATI drivers is something that I choose to take advantage of.
At home, I'm just getting ready to setup a Ubuntu 8.04 Server for a home file,print,dns,dhcp server. I've been doing testing in a virtual environment getting DHCP and DNS working with dynamic updates and documenting my learning experiences along the way. Got a few things to iron out with Samba and I think i'm ready to go.
Desktop: Ubuntu 9.04, AMD64 X2 4600+, Asus M2NPV-VM, 4GB RAM, Nvidia 7600GT
Laptop: Ubuntu 9.04, Dell Latitude E6400, Intel Core 2 Duo P8600, 4GB RAM, Nvidia Quadro 160M, Dell 1397 Wireless.