Here I assembled a list of software I use frequently for various tasks with good results.
Best of all, they are free and don't include any spy- or adware.
VLC - Media player
Mozilla Firefox - Web browser
OpenOffice - The Free and Open Productivity Suite
Foxit Reader - A small and fast PDF viewer
Picasa - Organize, edit, and share your photos
Skype - Make free calls over the internet to other people on Skype
AVG - Antivirus and Security Software
Smart Defrag - Efficient Defragmenter which makes your PC work faster
Glary Utilities - Powerful and All-in-one Utility to Fix, Speed up, Maintain and Protect your PC
ZoneAlarm - Firewall that Blocks Hackers from Infiltrating Your Home PC