I've been meaning to post something like this in a while but been putting it off. Coming off a fresh operating system install, I always often wonder what should I install first. Whether its an anti-virus or Microsoft Office suite for its business applications, we all have our basic essential necessity. By the way, in my opinion, anti-virus are overrated and is non-essential as long as you're careful about your surfing or email habits. That's another discussion. Going back to our necessity in our own PCs, I mean applications that will make your life more productive and your system running in tip-top shape as well. I have used quite a bit of applications in the past and have always tested whatever comes interesting my way. While I use a lot of applications, I only keep the necessities and the applications that I think can be useful and uninstall everything else.

My criteria for the top free essentials is well, it has to be free and among others:

1. Memory usage/benefit - is the extra memory consumption worth running it? While there's a lot of great applications out there, some of them use far greater memory than what it's doing or worth.
2. Longevity - how often is the application going to be used? If you have an application that has been sitting there for two to three months and has not been used, then you should re-consider uninstalling it as it serves no purpose but rather clutter your hard drive.
3. The best of the pack. If you're going to use an application, might as well use the best out of the rest.
4. It works. Does the application work as expected?

Here's my top recommended free essential applications:

• CCleaner - I have been using this application and is installed in every PC that I use. It is an system optimization tool that does a great job at cleaning temporary files, etc. as well as cleaning up the registry. It is a fast application that it cleans up the desktop in the fastest manner possible.
• Firefox 3 - If you're still using Internet Explorer as your default browser, Firefox beats IE with a handful of add-ins and optimized performance. The best thing about it is it makes your browsing experience much more enjoyable. I can't recall having to use IE except when testing web applications.
  
• Notepad ++ - This is an open source application that can be used to replace your Windows notepad. When I think of this application, it seems like a hybrid between Microsoft Word and notepad plus more. It has the same lightweight "feel" that the regular Notepad has but with support of syntax highlighting (useful for web editing), multi-view, colored printing and more. There's even an instruction on how to replace the default Notepad with Notepad ++.
• FeedDemon - When you go through several websites per day just to catch on the latest content such as New York Times or just a regular blog, then this free application is worth downloading for. You can go through all your favorite sites in minutes and skim through the articles and get to that article that you wanted instantaneously. The best part is being able to categorize it (ie. technology, blogs, etc.).
• Spybot Search and Destroy - When I hear "desktop essentials" this is in the top of my list and one of the first thing that comes in my mind. This application catches majority of the spyware and as long as you keep it updated, it ensures that your desktop is spyware-free.
• Revo Uninstaller - We often times find ourselves with applications that just won't uninstall or leaves tracks behind such as the installation folders and registry keys. This fixes those problems that I mentioned. It also has a cool "hunter mode" feature that you can drag on to a taskbar application so you can easily kill the process, locate its installation folder and even uninstall right on the spot.
• FileZilla - If you use FTP (file transfer protocol) to transfer files between your desktop and the server, then this light-weight application is what you need. This is another open source application just like Notepad ++ that essentially works pretty much the same way as the other paid version out there and has all you need to do FTP transfers.
• Winamp - I have this tied with iTunes as iTunes supports downloading of podcasts (correct me if I'm wrong). What I like about Winamp (same as iTunes) is its ability to tune in into Internet radios. I picked Winamp simply because it's customizable such as having the ability to skin the UI.

While there's plenty more applications out there, I can't really speak for them as I have never used them. I have only listed the applications that I feel that are essential and can be beneficial to everybody.