Switching from Windows or Mac to Linux on the desktop can be a little intimidating, but Ubuntu Linux is probably the most pain-free way to make the switch. The graphical interface looks a lot like Windows and is very easy to learn. Plus, Ubuntu comes with much of the best in open-source software that you would need for a small or home office installed by default. It's completely free, but commercial support is available.
32. Red Hat
While it's definitely targeted towards large enterprises, Red Hat Enterprise Linux is also a good option for larger small businesses, particularly those interested in installing Linux for servers. It's the most popular commercial distribution, so you can be sure it's tried and tested. Prices start at $349, but a free, non-supported similar version is available from Fedora.
Like Red Hat, SUSE Linux Enterprise and Open Enterprise Server from Novell are aimed at larger businesses but can be used by smaller businesses as well. Prices are also similar to Red Hat, and a free, non-supported similar version is available from openSUSE.
34. PDFCreator You don't have to buy the full version of Adobe Acrobat in order to create PDF files. This handy app can create PDFs from nearly any Windows program that can print files. The latest version also adds encryption and digital signature capabilities. Operating System: Windows.
Need to change an existing PDF document? PDF edit makes it possible to add text and annotations as well as make other changes to PDF files. Operating System: Windows, Linux.
If you're tired of downloading constantly updated and ever-larger versions of Acrobat Reader, you might want to try Sumatra PDF viewer instead. It's lightweight and very fast, and it can even be run off a thumb drive. Operating System: Windows.
37. OpenProj Billed as the open-source alternative to Microsoft Project, OpenProj is used by more than a million users in more than 140 countries. The desktop version (ideal for small offices) is available for free. For larger groups, the Projects on Demand SaaS version is available for $20/month. Operating System: Windows, Linux, Mac.
Even if you've never used a project management application before, GanttProject makes it very easy to schedule tasks and assign resources. It's also completely compatible with Microsoft Project file formats, and you can import and export to spreadsheets as well. Operating System: Windows, Linux, Mac.
If your small business is large enough to have its own Web server, Achievo offers flexible, Web-based project management, scheduling, and time tracking. It's especially well-suited for companies whose employees don't all work in the same building, and it even includes multi-lingual support for companies with employees in different countries. Operating System: OS Independent.
The Untangle Gateway Server incorporates a firewall, Web filter, anti-virus, anti-spyware, intrusion prevention and more into a single package. To use it, you'll need an old computer that you can hook up to your network as an Internet gateway. The basic software is free, or you can purchase a supported small business package with some extra features starting at $40/month. Operating System: Linux.
The community edition of Endian firewall offers a lot of the same functionality as Untangle and also requires an old PC that you can set up to run on your network as an appliance. In addition, Endian offers supported hardware or software appliances for purchase from the same site. Operating System: Linux.
Want to protect a single PC instead of a network? ClamWin offers good anti-virus and anti-spyware protection, but it does require a little more user intervention than most commercial products (i.e., you'll have to actually click on a file in order to scan it). Operating System: Windows.
Have trouble remembering all of your passwords? KeePass stores all your passwords in an encrypted master database so that you only need to remember one master password. Operating System: Windows.
For consultants, freelancers, lawyers, and other small businesses that charge by the hour, eHour makes it easy to track time spent by multiple employees on multiple projects for multiple clients. It's available in both a standalone version and a server-based version. Operating System: Windows, Linux, Mac.
The Drupal content management system features some of the best help and tutorials you'll find anywhere for walking you through the process of setting up your own database-driven Web site. The basic application includes features like blogging, forums, and contact forms, and the add-ons make it possible to add features like e-commerce and podcasting. Operating System: Windows, Linux.
Similar Drupal, Joomla is a content management system that lets you set up a database-driven Web site. It boasts a very active user community and the Web site offers an "Absolute Beginner's Guide" that can walk even the extremely non-technical through the process of creating a site from scratch. Operating System: Windows, Linux.
Developed by W3C, Amaya incorporates a Web browser and a Web page editor into a single application. Originally, it was designed to support HTML and CSS, but it has been extended to include some support for XML as well. Operating System: Windows, Linux, Mac.
Want to set up a Wiki-style site? MediaWiki is the app used to run Wikipedia, and it's also available for other organizations who want to take advantage of its collaborative editing capabilities. (Note that in order to use this app, you need your own server.) Operating System: Windows, Linux, Mac, BSD, Solaris.
System running slow? BleachBit helps you clean up your temporary files and other unnecessary junk to free disk space and protect your privacy. It can also shred deleted files so they can't be recovered and "vacuum" Firefox to make it faster. Operating System: Windows, Linux.