Open Source Applications For Windows
Not all apps need to run in Linux. Some people can't cut the cord like I have, and must still run Microsoft operating systems. Here is a short list of open source applications for Windows that those people can use and enjoy.
They DO Exist
There are open source applications for Windows that also have versions for other platforms. While there are Windows specific open source applications (Notepad++ comes to mind, and it's perhaps one of my favorite text editors) it's best to use the ones that have a version for every platform. If for some reason you find yourself using multiple operating systems in a short period, or have decided to change platforms, everything can stay familiar if you're going to be using all the same apps.
Open Source Email Application For Windows
An example of this is Mozilla Thunderbird. At work, I was designing kitchens on a Windows XP box. My main box was a Linux box though. Rather than perhaps have jumpy VNC sessions, I decided to use a KVM switch. But, it got to be a pain switching back and forth between the two when I couldn't remember what an email in Thunderbird (running in Linux) said. On top of that, XP can't seem to cope with USB KVM switches after too many times swapping back and forth. I think four was the most times I could switch without having to unplug stuff.
Anyway, I installed Thunderbird on the XP box. Just copied my profile over (via Samba) and all was well. Since the email account in question was IMAP, I could see everything to and from the account on both boxes. The interface was the same, because it was all Thunderbird, and I was able to get stuff done fairly quickly. This would have been more of a pain running Outlook on the Windows box and Thunderbird on Linux, and is a good example of cross platform open source applications that run in Windows.
Open Source Text Editor For Windows
Gedit is an open source text editor. It's the one I use most, and there's a Windows version. Really the only thing I require from a text editor is auto indent and language specific colored text. Gedit has both. I'd probably use vi, except that there's no auto indent that I can find…
I mentioned Notepad++ earlier. It's really an awesome program. One thing I miss is the ftp client it had built in. I've been able to work around that by just connecting to one via Gnome and SSH (kind of like sharing files with Windows, but with a remote Linux box over the encrypted ssh protocol) and editing files like they were right on my computer.
Geany is an app I liked using for a while. I used it because I was working on both Linux and Windows boxes, and wanted something consistent. I just never installed it on my newest laptop at home. After using the default gedit for a while, and finding out that there's a Windows version of it, I switched.
Jedit is an excellent example of a cross platform test editor. There's only one version because it's written in Java, and runs on any computer with a Java Runtime Environment installed.
Open Source Web Browsers For Windows
Mozilla Firefox is a cross platform web browser I'm sure you've heard of. I must admit that it's gotten a little heavy lately. I quit and started using Chromium (which also has a Windows version) because I felt FF had become a bit of a resource hog. I actually installed it (Firefox) yesterday on my android phone, and it turded out there as well… As much as I loved the browser for so long, I'd have to recommend Chromium to anyone looking at open source applications for Windows.
Chromium has a bit of an install process… Read Ian Channing's blog post about installing Chromium to see what you've got to do to get it running. As much as it initially looks like I pain, I have to agree with one of the commenters that the process will work well for someone who doesn't have admin privileges on their work computer. This will allow them to install Chromium right into their own Documents and Settings folder.
Open Source Image Editing For Windows
For people who like Photoshop, but don't want to pay for it or steal it, I'd recommend GIMP. It's a great program, and I've been using it for years. I think Photoshop 6 was the last one I used before switching, I believe around '02. GIMP is very powerful software. I think a professional graphic artist/illustrator could do well with just this program. In fact, I'd love to hear from any who are.
UPDATE: I started this post a few days ago, and tweeted about any professional graphic artists using GIMP exclusively. I've found one, and will be interviewing him in the next week or two. Alex Standiford has a blog chock full of GIMP related articles and tutorials. Head over if you don't want to wait.
There are a few apps that are just plain fun. I discovered them while running Linux, but it turns out that these also have windows versions…
Anyone have a model train? XtrkCAD is a layout planning application that runs in both Windows and Linux. I'm in the process of using it for my own N gauge railway.
Got a telescope? I'd be completely lost without Stellarium. Sure, I could get one of those crazy expensive telescopes that aim for me, but it's more fun standing out on my lawn, in the dark, with a laptop, wondering where the blazes such and such a star is at. It's also fun wondering what passing cars might think of the loon in his dooryard staring up at the sky… Stellarium is free, so using it for finding your way will enable you to get a telescope with better optics, rather than one with navigational bells and whistles that doesn't show much through the eyepiece.
I know I've missed tons of good open source applications for Windows, but these are enough to get a new person started.