Everything in bold below is what I consider an essential program that you should have.

• Ad-Aware Free - Cleanup utility - Free
  Excellent utility to remove spy/ad/mal-ware from your computer.  Works best when used along with Spybot Search and Destroy and CCleaner.
• Adobe Acrobat Reader - PDF Viewer - Free
  View/Read PDF files.
• Apple iTunes - Music player and management - Free
  Excellent music and video management program.  Doesn’t support many video and audio formats, which is a bit of a bummer.  But otherwise works perfectly.
• Audacity - Audio Editing/Recording - Free
  Excellent yet simple audio editing program.
• Avast Anti-virus - Anti-virus/Anti-Malware - Free (for home use)
  Perfect for home use.  After installing the program, follow these instructions and go to the Avast section.
• CCleaner - Cleanup utility - Free
  Easily removes garbage and temporary files from your computer. Recommended to run this once a week.
• CuteWriter PDF - PDF Maker - Free
  Will let you convert practically anything to a PDF file.  Install this, then “print” whatever you want into a PDF file. 
• DeepBurner - CD/DVD Burner - Free
  CD burning programming. 
• Essential Codec Pack - Audio/Video codecs - Free
  Drivers/Software that allows your computer to play practically any type of audio or video file.
• Google Chrome - Web/Internet Browser - Free
  Excellent internet browser and replacement for Microsoft Internet Explorer and Apple Safari.  Automatically is kept up-to-date and super fast.
• FreeRip - Audio/Music converter - Free
  CD ripping program.  Simple and very effective.
• Format Factory - Audio/Video/DVD conversion program - Free
  Allows you to convert almost any image, video, or audio file to a different format.  Simple to use and very effective. 
• HandBrake - DVD conversion - Free
  With the use of a DVD decryption tool like Slysoft AnyDVD, this program will convert any DVD to a different file type.
• KeePass - Password manager - Free
  Excellent program to securely manage all the usernames, passwords, etc. from websites and services you access. 
• LogMeIn - Remote access/control program - Free
  Great service that allows you to access your computer from anywhere in the world, as long as your compuer is powered on. 
• MergeMP3 - Audio/MP3 combiner - Free
  Merges MP3 files of the same bitrate without recompressing the MP3s (avoids losing quality).
• Microsoft Office - Word Processing, Spreadsheets, Presentations, etc. - ~$120 for Home/Student version
• OpenOffice - Word Processing, Spreadsheets, Presentations, etc. - Free
  Microsoft Office alternative. Very compatible with Microsoft Word, Excel, PowerPoint, etc.
• Orb Media - Personal media broadcasting - Free
  Service that lets you securely view your multimedia files (audio/video/etc.) from any internet enabled computer on the internet. 
• Paint.net - Image editing - Free
  Excellent image editing program. Fairly simplistic, but works very well.
• ScreenHunter - Screen capture utility - Free
  Tiny utility that lets you easily take a screenshot of your computer screen.
• Slysoft AnyDVD - CD/DVD utility - ~$80
  Removes DVD/CD encryption from almost any CD, DVD, Blu-ray, or HD-DVD.
• Slysoft CloneCD - CD/DVD utility - ~$40
  Can copy a CD/DVD exactly to a blank CD/DVD.
• Slysoft CloneDVD - CD/DVD utility - ~$40
  Copies a DVD of whatever size to a normal 4.5gb/4.7gb writable DVD.
• Spybot Search and Destroy - Cleanup utility - Free
  Excellent utility to remove spy/ad/mal-ware from your computer. Works best when used along with Ad-Aware Free and CCleaner.
• SugarSync - Backup utility - Free for 5gb
  Near-perfect online backup and synchronization service. Automatically backs up all your important files to an online location, that way if your computer dies, you can easily recover your most important documents, images, and other stuff. Since everything is backed up online, you don’t have to worry about your files being lost if your computer dies, house gets flooded, stolen, etc.