[RESOLVED] Get User OS

[Reiners]

Hi!
I implemented a log function in my scripts to log IP adress, time of visit, browser and what have you from my visitors.
Now I would like to add the operating system. I already used "$HTTP_USER_AGENT" which gives me the following output:

Opera/9.00 (Windows NT 5.1; U; en)

Can I guess the Operating System (like Windows XP or Windows 2000) with these information? Or how do i get this information?
I think it is possible to get the visitors OS because I saw this site:

http://www.anonym-surfen-test.de/test/zugangsdaten

Many thanks for reading,
Reiners

[Reiners]

by looking into the code of "phpsniff 2.1.3" I found out that the information in the brakes can be translated into the following:

$OS = $HTTP_USER_AGENT;
$OS = str_replace("NT 5.1", "XP", $OS);
$OS = str_replace("NT 5.0", "2000", $OS);
$OS = str_replace("9x 4.90", "98", $OS);

maybe it helps someone.