Migrate off Windows XP and change to a supported version of Windows. It is insecure and there is no way to make it secure.
You can come up with all the 'reasons', 'excuses' and justifications you want but no amount of "I'm safe", "I'm behind a firewall", "I know better" will impress most people in the channel. And no, the 'registry hack' to pretend you are using XP Embedded doesn't impress anyone either since XP Embedded isn't getting updates for major portions of Windows XP so you are still missing critical patches to the OS.
Windows XP was released to the retail market in August 2001.
It's time to move on:
Insanitybit: Windows XP – Abandon Ship (discussion of some common mitigations and their potential strengths/weaknesses)
Insanitybit: Windows XP Support Has Ended (more on the above)
Windows XP is not 'abandonware' since Microsoft still holds Copyright. Call Microsoft or a lawyer to confirm if you feel the need.
Windows XP Embedded is NOT XP Workstation
It is a specialized distribution not generally available to the consumer so continuing to argue that it works as an approach is not really viable since it requires a serious skillset to maintain in highly specific or regulated environments. Many versions of which are also out of support or soon to be out of support as well. The versions that are not yet out of support are not full XP versions but subsets designed for deployment to embedded environments in often highly protected/isolated environments, not as a general workstation.
From this article:
Improved security with newer versions of Windows
It’s also worth noting that the security protections in Windows have evolved significantly since Windows XP was released. For example, the integrity mechanisms available in later versions of Windows support features such as User Account Control and IE Protected mode by restricting access to processes, files and registry keys. The best form of defense is to use newer versions of Windows Embedded, such as the recently released Windows Embedded 8.1 Industry. Windows 8.1 includes a number of security improvements, including secure and trusted boot to ensure that a system is not tampered with during the boot process.
As noted here for these security updates, these are not for general consumers:
MyOEM is a restricted-access portal for OEM partners with a valid license agreement with Microsoft or with a Microsoft Authorized Embedded Distributor and for internal OEM employees. The product downloads on MyOEM are available only to Embedded Distributors and Embedded Indirect partners.
Lifecycle for various XP based embedded OSes since it keeps coming up in channel.
Windows XP Professional for Embedded Systems. This product is identical to Windows XP, and Extended Support has ended on April 8, 2014.
Windows XP Embedded Service Pack 3 (SP3). This is the original toolkit and componentized version of Windows XP. It was originally released in 2002, and Extended Support will end on Jan. 12, 2016.
Windows Embedded for Point of Service SP3. This product is for use in Point of Sale devices. It’s built from Windows XP Embedded. It was originally released in 2005, and Extended Support will end on April 12, 2016.
Windows Embedded Standard 2009. This product is an updated release of the toolkit and componentized version of Windows XP. It was originally released in 2008; and Extended Support will end on Jan. 8, 2019.
Windows Embedded POSReady 2009. This product for point-of-sale devices reflects the updates available in Windows Embedded Standard 2009. It was originally released in 2009, and extended support will end on April 9, 2019.