I am going to be setting up an old Pentium 4 laptop to dualboot Windows 98 and XP. Since it has a discrete GPU, a floppy and dvd-drive that don't need to be removed to also have the battery attached it seemed perfect for retro PC games.

I highly doubt I will connect the system online, but in any case whether I do or not I want to update both 98 and XP as much as I can, more for any features/bugfixes that were added after the retail disks than any sort of online security since I doubt I can have that anyway.

In the case of 98SE... was there even an update system for Windows98? It's been so long I can't remember, but I think I recall there was some Windows Update application that came with it? Regardless though, I assume this application no longer functions? So are there any 3rd party applications or update packs I can install to bring Windows98SE up to date just for any fixes it might have had past the retail 98SE disk? Also, are there any 3rd party unofficial update packs or other patches/improvements one can recommend? I have heard of this unofficial "SP3" pack for Windows98, but I am not so sure if it's a good idea or not. I have heard some people mention to install it, and others to say to just go with vanilla 98SE and that it can cause issues. Any opinions on that? Or any other 3rd party update packs/patches/improvements to 98SE?

And in the case of XP, are there any recommended ways to update it (Yes I am aware new updates stopped years ago) and any aftermarket update solutions? Since XP no longer supports modern SSL that just about every website nowadays requires I don't think I can even connect to the official WindowsXP update anymore? I remember hearing about something called "nlite" that apparently applies a few more unofficial updates/patches/features. Is this any good? Is it something I have to apply to a somehow already fully updated XPS3 install or does it apply the missing updates to a base retail XP S3 disk? And if it's not recommended, are there any update packs/recommendations one can recommend?

Just to clarify, this is not going to my daily driver or anything. I have several modern systems to use for actual internet and daily use, I purely want to set this system up to play old Win95/XP games that don't run well on modern systems... but also don't run well on or are too advanced for something like DOSbox or PCem/86Box to handle.