I have two Linux systems:
One is a Compaq notebook that used to run Windows XP. It has a 2.0 Ghz AMD processor and 2 gigs of RAM. When I switched to Ubuntu (a Debian Distribution), I was pleasantly surprised to find that my notebook not only ran cooler, but startup was 2 minutes faster and ran for 3.5 hours on one charge instead of the 1.75 hours it used to run for with XP.
Ubuntu with all the programs I have on it only takes up 10 GB of hard drive space, while XP with all the programs I had on it took 28 GB. I have WINE installed so I can run some windows only apps like EES. Luckily for me, the really important application I must have for engineering (Matlab) is available for Linux and it runs perfectly on Ubuntu. I also found OpenOffice to be equivalent to Word and PowerPoint for my needs and Gnumeric Spreadsheet easier to use than EXCEL for what I need it for. The computer is now totally unique, customized just for me.
Using it is easy, installing programs on it is an experience that requires some learning. Matlab, for example, took me 3 tries to get installed. I failed to realize that it was trying to install to the root account, which you do not control in Ubuntu. Programs such as Matlab must be installed in the root of the drive or they won't work, so I had to fake root privileges to install it. While it may sound like a pain in the rear, I'm willing to live with it because it makes Ubuntu so secure that when coupled with a decent Firewall it is virtually impossible to install a virus or hack into the system.
Another great feature about Ubuntu besides its great security is that it is on my University's list of approved secure operating systems, so I do not have to run any Cisco programs to access the network like those who use Windows do. When I had Windows, I had to run both Cisco VPN and Cisco Clean Access. Neither of these programs worked very well the way the University had them configured and they crashed all the time, leaving me without internet or my network drive. Ubuntu automatically logs me into the internet when I launch my browser and it automatically maps my network drives at startup and authenticates them when I log onto my user account.
My other Linux system is an Eee Pc. I bought it last week and it is an awesome little machine. It came with a modified version of Xandros as the OS. I enabled a full desktop in addition to the easy mode, but was still unsatisfied with the lack of customization features present. I was unable to add simple programs to Xandros that my Ubuntu machine had and that really hacked me off since I wanted the two computes to mirror each other as much as possible. After a little searching I found an Eee Pc operating system that was closer to Ubuntu called eeeXubuntu. It is a Ubuntu variant written to work specifically with the Eee Pc. It has all the features of Ubuntu but used XFCE as the desktop manager instead of GNOME. Installing it was easy and out of the box it worked almost flawlessly. I did have to make some modifications to get it to write to the SSD drives less since they can't handle as many writes as a traditional hard drive, and I did another mod to make it use less power. I finally installed a script that made the combination function keys work correctly and display the on screen confirmations that the Eee Pc had in Xandros.
All in all I love Linux with one small exception: Itunes does not work under Linux without Crossover Office, which I will not pay for (Everything is supposed to be free with Linux, so paying for an app to put another free app on the computer goes against everything Linux stands for). I have found a good alternative in Songbird, but it does not have a store like Itunes. Once Apple writes Itunes for Linux or Crossover Office becomes free, I'll be 100% happy with my Linux.