Hello and Welcome to LinuxQuestions,
Squid is a HTTP/HTTPS/FTP proxy server and has nothing to do with sharing data, printers and DVDWriters. Basically, it only allows you to control access to the web and cache contents to speed up web access. What you need to look at for sharing printers using your Linux box is CUPS
, for the data you can set up a shared Samba directory that all your WinXP clients can access. Also, when posting a question it's always a good idea to mention what distro and version of Linux you are using.