People, be careful for UG in advance, but I think it's useful for everyone, if anyone knows better - write:
List of free home / office programs

OpenOffice (analogue to MS Office, except for the mail client)
7-ZIP (archiver, analogue to WINRAR)
GIMP-2, PhotoFiltre (PhotoShop analogues)
Gom Player (video player, holds all formats in general)
Mozilla Thunderbird (analogue to MS Outlook)
AVAST (antivirus, home version free, only need to register)
AIMP (analogue of WinAMP)
I personally tested it all, very good :)
All progi are freely distributed, free, support the plz, who has not