For XP this kills the service entirely and there is no way to turn it back on unless you or some form of 3rd party* software you have installed turns it on. Period. Like, no discussion. Automatic updates were implemented with XP and that is the end all be all for updates, service off = the update software cannot be run. This could be different for 7 as it's newer but I highly highly doubt it. For whatever reason you may want to use XP some more I suggest ditching stock iterations and find yourself the Integral copy that is substantially better anyways, it's what I use. It doesn't even have the update service built in anymore. It also comes with native NVMe, USB3, modern SATA, and networking support built in with a browser that works among other things.I tried the usual update-disable method described on many sites (for example: https://www.computerhope.com/issues/ch000538.htm#xp), and it was only effective for about a week in stopping the stealth downloads of KB junk to my XP Pro. It took the previously mentioned software to lock down whatever backdoor M$ was using. The fact M$ should of stopped this back in 2014, yet was still at it as of one year ago, means their credibility is nil with me....especially where EOL/EOS is concerned. Hopefully it will be different with Win 7 Pro, but I'll not be turning my back nor letting my guard down.
*And by this I mean any AV, software update program, security center, security essentials, anything like that.