I use Windows and Linux (I own PC's, always have, always will. Macs are overpriced and I am not going to overpay for normal PC hardware that is licensed to run an OS that isn't compatible with very much).
Linux has very good support for basic stuff:
Web Browsing ------------- Firefox
E-mail -------------------- Thunderbird, Evolution, Firefox (web based e-mail)
Office -------------------- OpenOffice 2
Instant Messaging -------- Gaim / Pidgin
Media Playback ----------- VLC Media Player, MPlayer, Totem, Rhythmbox, Amarok, XMMS
Linux also has some creation software that, for most people, functions equally as well as their Windows counterparts:
Image Editing (Photoshop) ------------------ The Gimp (I think it's easy...)
Audio Editing ------------------------------- Audacity
Webpage Editing (Dreamweaver) ------------ Nvu Page Editor
There are also some other good apps:
DVD Ripping -------------- DVD:Rip
Windows compatibility ---- Wine
The only thing I haven't found for Linux is (what I consider) a decent video editing application. This may be my experienced "semi-professional" side, but I have long used Pinnacle Studio (version 8 and then 9 Plus) and Sony Screenblast 3.0 (now called Sony Vegas) for video editing. I use the blue-screen and non-linear editing modes of these programs. I like Screenblast the best because it has a good layout and strong features.
The closest thing out there is Cinelerra, but that is:
-Difficult to install (wasn't in the repository at first, then it installed but wouldn't start, finally did get it working after several tries)
-Poorly laid out (Instead of a simple, easy single window, each component has its own window. At the time, I only had a 1280x1024 monitor, which isn't really that small, but the screen was really cramped. Screenblast ran very usably on a 1280x1024 monitor. I have a 1680x1080 now, but Screenblast still manages the screen much better)
-Confusing interface (with all the different windows, it was hard to tell what was what. It had two video screens, a track for editing, and some other stuff)
-Relies on other codecs (Ubuntu doesn't install the GStreamer codecs by default [which is stupid, because there's probably no one out there who doesn't install them as soon as they get the OS installed], so you have to install those first. Finding other codecs can mean adding custom repositories or working with packages...I'm editing video, not administrating a computer...it should do these things automatically)
I think if it could just fix the interface and make it one app in one window, it'd be much better (even if I have to install things manually, not like any other Linux app is any different).
Before you say I haven't tried Linux recently, I have (got 8.04 as soon as it came on the page [before it made it's way to the front page lol] and ordered pressed CD's as well).