Many commercial office packages have open source, or at least free, alternatives available. Many of these products are also available across platforms. Many conform to a published, open standard.
Office Software
Rather than Mi¢ro$oft Office, try OpenOffice with:
try as rather than OOo Writer word processor M$ Word OOo Draw drawings M$ Visio
and
M$ Publisher
OOo Calc spreadsheet M$ Excel OOo Impress M$ PowerPoint OOo Base database M$ Access
These are able to read and write Mi¢ro$oft documents, and write PDFs.
Many extensions are available.
OpenOffice does not contain a true replacement for Publisher or Visio.
Rather than Mi¢ro$oft Publisher, try Scribus.
Unfortunately, this can not read or write Publisher documents.
Rather than Mi¢ro$oft Outlook, try
Mozilla Thunderbird as email client
Mozilla Sunbird as calendar application
These are not as extensive as Outlook in functionality, but may be better for home use.
Drawing and Artwork
Rather than Mi¢ro$oft Visio, try Dia or Inkscape.
Rather the Adobe Photo$hop, try the GIMP.
Browser
Rather than Mi¢ro$oft Internet Explorer, try Mozilla Firefox as browser. (See also my post on extensions.)
Mathematics and CAS
The computer algebra system Mathematica from Wolfram Research is very expensive.
For alternatives, see my post on CAS software.
Backup
I’d recommend Cobian Backup.
Source Control
Rather than Mi¢ro$oft Visual $our¢e$afe, try Subversion. (See also my subversion posts on tools and links.)
There are many other free and open-source source control tools out there, including some very interesing ones. I like Subversion partly because it is relatively light-weight, configurable (yet with very sensible defaults), easy to install, and has active development and support communities.
Miscellaneous
To create PDF files from any application, try PDFCreator.
Real Player is horrible adware and Windoze Media Player is pretty horrible too; try instead Real Alternative, which includes Media Player Classic.