Here are my favorite freewares.
AVG Anti virus free edition - Security first. If you don't like AVG, try any other free anti virus. But don't allow them to mess you up.
Notepad++ - A must for programmers. What I liked most is its XML handling features. Just try it, you will love it.
Zip Genius/7 Zip - The free alternatives to WinZip.
WordWeb - A free dictionary. Rests silently in you systray, just a double click away.
Visual Studio Express Editions - Remember the fuss made by Sun a decade or so ago by giving Java SDK free of cost. Now companies give full IDEs for free. Microsoft Visual Studio express editions help professionals to learn technology without spending money. Not recommended for professional development, but no one will stop you if you want to do.
Paint.NET - The big brother of MS Paint. You can even use layers.
Arena Chess - I love to play chess. Try this, it is not that much user friendly, so you may take some time to learn the features.
BullZip PDF Creator - Create PDF files from any application.