You can practically do all the internet stuff from linux (email, web, chat, video conferencing, phone, etc.) They even include office applications ranging from database to spreadsheet, and all the software development tools for virtually any existing programming languages.
I installed Ubuntu once and it was nice, but since I'm an old time RedHat/Fedora user, I didn't find it quite fitting for my needs (I also run file server for windows, web server, etc.) so I went back to Fedora.
The only problem is that commercial games are not that many. I ran Quake 2, etc. from id software using my windows games and linux software without problems.
But I need to run Tomb Raider 1,2,3 and although I successfully ran Tomb Raider 1 using dosbox without much problem, I am not sure I can do that with Tomb Raider 2, 3 under linux.
There are windows emulators like wine or cedega, but I haven't tested them extensively. I ran Red Alert 2 and most C&C series without problems, but they were somewhat slow and not all applications run fine.
I also tried qemu running windows in a virtual machine inside linux, and most windows non-game applications run fine, but due to speed, games seem to be quite slow.
I know some game publishers provide linux versions, but I would also like to see classic games like StarCraft running under linux. Remember, I paid cash to buy Tomb Raider Trilogy for Windows, even though I don't have Windows anymore, in the hopes that I could run it under linux using some emulator. So publishers should know there are markets for linux games. So far, I'm thinking of returning it. I already own Tomb Raider 1 which is how I tested under linux, but I haven't torn the wrap on the Trilogy yet.