其.NET框架我可以依靠的版本

我在写一个应用程序，发现在电脑上存在哪些功能。用户将进入一个网页，下载应用程序并执行它（与所有适当的警告，这是不是间谍软件）。该应用程序将使用标准的MS API来确定诸如连接速度，已安装的内存，防火墙卫生等编写的应用程序是没有问题的，我可以使用脚本主机，C＃，C 等。现在的问题是，如果我选择C＃是那里将安装.NET窗口的某味任何保证？目标电脑是XP SP2或更高和Vista。

I am writing an app to discover what features exist on a pc. The user would go to a web page, download the app and execute it (with all the appropriate warnings, this is not spyware). The app would use the standard MS api to determine such things as connection speed, installed memory, firewall health, etc. Writing the app is not a problem, I could use Scripting Host, C#, C , etc. The question is, if I chose C# is there any guarantee that a certain flavor of windows would have .net installed? The target pc is XP SP2 or better and Vista.

感谢您的帮助。