~~ Anti-virus and malware protection
No matter what operating system you run you need to protect your computer with an anti-virus program and malware. Windows is the most susceptible to these types of attacks, but if you are running Macintosh or Linux you can get infected as well. Of course those two operating systems are less likely to be attacked but they still have as many bugs and potential vectors for attacks. In fact, I almost consider them less secure in some ways because there are not as many programs designed to protect the system or help you clean it. Like determining that you have a root kit in Linux is pretty hard.
Today, many Anti-virus and Malware programs are all the same but you want to be sure that you do get a quality programs. Currently, I have mixed opinions on Anti-virus to use but like to stick to a free one - AVG. That might change in the future but I have been running them for a while and had no issues. For malware, though, I take things a bit more serious. The program I am using and recommend right now is: SpyNoMore
Why do I like them? Their Custom Fix technology that ensures your safety. It allows you to upload the scan report to their server for manual analysis by their Technical Staff. They will send a customized Fix back to you via SpyNoMore, thereby guaranteeing full and permanent removal. No other anti-spyware software offers such feature!
~~ Backup solutions
There really are dozens of free and commercial back up solutions for your computers and files. Many of these actually store your files locally and put you at risk because if your house was destroyed - your files would be gone as well. What you need is an online offsite backup solution. This way if your computer is stolen or damaged in any way, your data is safe because it is being backed up in another remote location.
I only use one company for this because they are one of the first and actually offer a few Gigs free of storage. If that is not enough, their payment plan is very cheap and allows you unlimited storage. This is great because most services do not allow that. Also they recently upgraded their software to allow you to backup in two locations.
The brower wars continue between the big boys of Microsoft, Firefox, Apple, and Google. In this world it really is a matter of preference as to what browser you should use. I have tried them all myself and really find it hard to decide. As a web page developer I actually hate that there are so many different browers because it really is a pain to code webpages to look the same across all of them.
What I do suggest though is that you make sure your security settings are enabled correctly on whatever browser you use and that you are always careful that you do not get caught by a phishing scheme. Also I strongly suggest that you do not do financial banking on the same computer you do general browsing on unless you are very careful to keep it clean of potential infection and you are sure you do not browse to dangerous sites.
~~ Compression utility
A good compression utility is definitely something everyone needs. Windows finally has one built in but it still is not as good as some of the other ones you can get especially since there are many forms of compression like zip, rar, etc.
The application of choice that I use is 7-zip located at: http://www.7-zip.org/
~~ Disc ripper and creation utility
Creating an audio or data CD/DVD, ripping audio to a CD, or creating a CD from a .ISO file is always useful.
My recommended solutions is CDBurnerXP located at: http://cdburnerxp.se/
Email really was a great thing to happen to us for communication but it certainly can cause a lot of problems as well. Being able to manage your email is important and I really do like to use Mozilla Thunderbird because of the different options it provides. It has filtering ability, security options, tabbed emailing, etc.
Get Mozilla Thunderbird from here: http://www.mozillamessaging.com/en-US/thunderbird/
~~ FTP, SFTP, and SSH Utility
For my day and personal jobs I connect remotely to many computers. My websites require me to upload files and do other things. FTP and SSH is definitely something that is critical to me. There are many commercial programs capable of doing this but my free recommendations beats them all.
Get Filezilla here for FTP and SFTP: http://filezilla-project.org/
Get Putty here for SSH: http://www.chiark.greenend.org.uk/~sgtatham/putty/download.html
There are dozens of different multimedia programs with different capabilities and limitations out there to help you view video files or record audio. But there are only so many that seem to always be used by everyone. The top programs are:
Get Audacity for audio here: http://audacity.sourceforge.net/
Get VLC for video and DVD playing: http://www.videolan.org/vlc/