Firefox - Everything you need when you are connected. With its add-ons, you can do anything you wish.
Irfanview - For image
Notepad++ - Simple notepad replacement to see code files without loading huge IDES. It has nice syntax coloring, and formating feature for all languages you know.
Filezilla - Using it when transferring
7zip - Very cool archiving software that you can use instead of winrar, winzip etc... Support many formats of archives.
Bsplay - Free and old version of BSPlay. New version now costs money ;) After installing codec package, you can watch all types of video.
Winamp - Listen to the music, radio and online tv.
Bitlord- Sometimes you need to download from torrent world. Bitlord is the coolest and simplest client. i like it, but the old one. New version looks like very complex.
Pdfcreator - Convert your any types of files into PDF.
Gtalk - Easy to use and simple chat that is integrated with Gmail. I Love Google.