Where to obtain the WinHttp 5.1 redistributable?

i'm trying to find the redistributable for Microsoft WinHttp 5.1.

Some older Windows 2000 machines in the enterprise do not have it.

Microsoft's website says:

Redistribution

WinHTTP 5.1 is available only with Windows Server 2003, Windows XP with Service Pack 1 (SP1), and Windows 2000 Professional with Service Pack 3 (SP3).

Is that the only method?

From serverfault Ian Boyd

• Someone on MSDN mentioned that they thought it came with IE6SP1(scroll down for the comments). However, you should be able to extract the file from the Win2k Service Pack.

  Having used 2000 for a few years, I can't recall a time when updating to SP3 or SP4 caused any issues; if anything, Microsoft got their service packs right and with each update things seemed to be "a little better", although that is a subjective measure and not a qualitative analysis. If possible, I'd consider updating to SP4 (and Update1 as well), given that the service packs have been out for a considerable time now.

  From Avery Payne

• The way to get WinHTTP 5.1 installed on Windows XP without any service packs is to install KB842773. This may also work on Windows 2000, but I have no way of testing this currently.

  From Strom