I have been asked by many people over the last few weeks about which anti-virus software they should buy so I thought I would point out a few of the free resources out there.

A good site to start with is www.freebyte.com which has links to many good products.

Anti-Virus: I have tried AVG's free product and it seems to perform well on XP. Haven't yet tried on Vista.
Current release is at http://free.grisoft.com/freeweb.php/doc/5390/lng/us/tpl/v5 which is v7.5.

Office Software: Have a look at Open Office. The current version can open and save in common Microsoft formats and is suitable for most home or small business use.
Go to http://www.openoffice.org.

ZIP file compression software: I use Zip7 which can be found at http://www.7-zip.org/

I'll publish more when I have tested products on Vista.