Get Windows OS version

You can't rely on the PB Environment Object because it doesn't return enough details. For on W2K system, the Environment returns NT as the operating system. A better way is to call directly the Win API to query the OS version.

[local external function]
FUNCTION ulong GetVersionExA( REF str_osversioninfo lpVersionInfo ) &
LIBRARY "kernel32.dll"

the required structure

[str_osversioninfo]
ulong dwOSVersionInfoSize
ulong dwmajorversion
ulong dwminorversion
ulong dwbuildnumber
ulong dwplatformid
CHARACTER SZCSDVERION[128]

the possible values

dwMajorVersion
    Windows 95: 4
    Windows 98       4
    Windows ME       4
    Windows NT 3.51  3
    Windows NT 4     4
    Windows 2000     5
    Windows XP       5

dwMinorVersion
    Windows 95       0
    Windows 98       10
    Windows ME       90
    Windows NT 3.51  51
    Windows NT 4     0
    Windows 2000     0
WINDOWS XP       1

To distinguish between 95 and NT, you also need to check the dwPlatformId value

VER_PLATFORM_WIN32s             0
VER_PLATFORM_WIN32_WINDOWS      1 // WIN95
VER_PLATFORM_WIN32_NT           2 // NT

and from Powerscript, for example

str_osversioninfo lstr_osver

lstr_osver.dwosversioninfosize = 148
GetVersionExA( lstr_osver )

IF (lstr_osver.dwmajorversion = 5 AND lstr_osver.dwminorversion = 1)  THEN
    MessageBox("", "Running on XP");
END IF