Weiterführende Links:
http://www.valvesoftware.com/privacy.htm
(...)By using Valve's online sites and products, users agree that Valve may collect aggregate information, individual information, and personally identifiable information, as defined below.(...)
"Aggregate information" is information that describes the habits, usage patterns, and demographics of users as a group (...)
"Individual information" is information about a user that is presented in a form distinguishable from information relating to other users (...) This information may be used (...) for internal marketing studies, or simply to collect demographic information about Valve's users.
(...) "Personally identifiable information" consists of a user's name, email address, physical address, or other data about the user that enables the recipient to personally identify the user. (...) Valve's collection of personally identifiable information may be a requirement for access to the product or site.
(...) Valve does not use cookies on their websites; however, Valve does store information on a user's hard drive that is used in conjunction with online play of Valve products. This includes a unique authorization key or CD-Key that is either entered by the user or downloaded automatically during product registration. This authorization key is used to identify a user as valid and allow access to Valve's products. (...) Valve software automatically generates and submits to Valve bug reports upon a crash or other fault in the Valve software. This automatically generated bug report information may include information about other software or hardware on a user's system.
(...) Valve has taken reasonable steps to protect the information users share with us, including, but not limited to, setup of processes, equipment and software to avoid unauthorized access or disclosure of this information.
(Hervorhebungen durch mich)
Man will ja keine Häme verbreiten, aber wenn sie mit den Nutzerdaten genauso sorgfältig umgehen wir mit ihrem Sourcecode ...

http://www.steampowered.com/index.php?a ... _agreement :
(...) You understand that Steam may automatically update, pre-load, create new versions or otherwise enhance the Steam Software and accordingly, the system requirements to use the Steam Software may change over time. (...)
=Abgabe der Kontrolle darüber, was auf dem eigenen Rechner installiert wird - ein wunderbares Einfallstor für Trojander uns Viren. Also, ich werde HL2 sicher nur auf einem separaten Rechner mit einem eingeschränkten Benutzerkonto betreiben, das ist für mich schon mal sicher.