Open Source O.S. (Linux) and Freeware

Most Linux Operating systems are FREE.  This may be a good alternative to Windows. 
Note: Most Linux systems will require a little computer knowledge and you may not find it as user friendly as Windows.  Do your research before jumping in.

Ubuntu: : 
Ubuntu might be the most popular Linux system.

Puppy Linux: : 

D.S.L.: : Great for older desktops and laptops with a small amount of RAM.

AVG Antivirus: 
Free antivirus software.

CNet Download: 
Great site for free downloads.

avast! Free Antivirus: : Great free antivirus