I have been using PCs and installing software packages for many years. My biggest gripe with software manufacturers is the constant changing and upgrading of software. There isn't a single software package ever written that hasn't been upgraded at least once. My gripe isn't that I am not grateful for the improvement(s) but all too often the act of upgrading is like taking a big risk that your PC or laptop might not accept the upgrade and you will find yourself screwed, so I recommend that people upgrade only if you know you will actually benefit from the improvements that the upgrade will hopefully bring. I suggest that when ever you install software that you locate and immediately turn off the automatic update option. 

Audio

iTunes (free) is not just great for topping off your iPod but it is also great for importing music (ripping music from CD format to your hard drive in .mp3 format) and creating your own custom audio and .mp3 format CDs for your listening pleasure. The music cataloging features are also well thought out. The audio related Visualizations in iTunes are extremely entertaining.

Winamp (free but there is a pay version) is great for playing CDs but it's Shoutcast Internet Radio feature is it's most valuable component. Another necessary application to install along with Winamp is Streamripper (free). Streamripper opens when ever Winamp is open and runs in conjunction with Winamp, listening to what ever Winamp is playing. If you are listening to an Internet Radio stream with Winamp, Streamripper can record what ever music is playing. It creates a folder on your desktop for each radio station you stream and then it fills that folder with .mp3 files. It even assigns the proper names to the music files it records!

Audacity (free) is a great application for editing audio files including .wav and .mp3 music files.

Images

Picasa (free) There's just no getting over the fact that Picasa IS free and it IS a wonderfully thought out application that ties together with Google to make sharing your pictures with family and friends easier than ever. Picasa can also perform a huge number of image editing functions but Picasa IS NOT a stand-alone image editing software package. The important function that it does not do is "resizing". For that specific function I recommend Paint Shop Pro (Version 5 if you can find it) because as complex as it has become over the years, it is still as user friendly as Windows based software applications can get.

Video

There are many, many applications available for ripping DVDs, copying DVDs and  viewing and editing video files. Most of them are garbage, a few of them actually perform well if you have a newer PC that has a fast processor and enough RAM.

DVD Decrypter (free but there is a pay version) rips "most" copy protected DVDs to your hard drive.

Handbrake (free) creates high quality digital copies of your ripped DVD movies. It can create a variety of video file formats that can play on just about any portable video file player.

DVD Shrink (free) creates a DVD copy of the DVDs that you have ripped to your hard drive.

DVDFab Decrypter (free but there is a pay version) is a one step DVD copying solution.

Remember that it is illegal to make copies of your DVD movies! It is also illegal to distribute any software that breaks the copy protections on a DVD.

Anti-Virus

Avast (free but there is a pay version). Anti-virus software is the most problematic software you can install on your PC. The two best known names, Norton (owned by Microsoft) and McAfee are subscription based applications and often come pre-installed on new systems. They are not the only options available. The most important thing to remember is that you should only install one (1) anti-virus application. Removing this pre-installed software is the very first thing you should do with your new PC otherwise you will be constantly nagged to pay up.

Web Browsers

Firefox (free) is currently the best web browser available and there are many "add-ons" that make it fun to use. Unfortunately, Microsoft's Internet Explorer is still necessary for some aspects of Java and Flash to function properly. Opera and Safari are still not acceptable alternatives for Windows users.

System Maintenance

Regcleaner v.4.3 Build 780 (free) is a great application for uninstalling software and cleaning up your system registry if you can still find it. The newer versions work for 30 days then you have to pay.

Word Processor

Open Office (free) is a complete WP application with all of the bells and whistles of Microsoft Office but none of the regret or bad feelings.