wondering if it would work for me to create surround sound or 5.1 audio CDs or DVDs.
No. OBS isn't a DVD authoring tool. It's a tool to record from original audio and video sources (camera, microphone, PC/console game capture) and create either a file that contains this recording or live stream this to some streaming service.
It's no tool to postprocess existing material, and it's no tool specialized to process audio. It doesn't have an output to create a CD/DVD.
If you want to create music, use a DAW (Digital Audio Workstation). A DAW is a program that records, uses/creates samples and simply produces music. There is a plugin system for DAWs called VST, and everything you might want from a music processing app can be supplied by some VST plugin. (OBS also supports VST plugins, but forget this for your case. You want to create music and no videos, so get a DAW app and forget OBS).
If it comes to your hardware and software, XP and everything around this is completely and utterly obsolete. Hardware and software is dwarved in comparison to today's features. Stuff you do on your system that requires one day to work on, might be one menu option on a modern app today you click and don't even have to wait for the result.
If you want to be productive, get current hardware and software. There is free DAW software. Trying to find software and workflows for your old system is wasting your precious time by dismissing all the modern stuff, and you will not even succeed in finding something. Instead, invest your time with becoming familiar with current operating system and current apps.
Get yourself a new Window 11 PC and start fresh. Keep nothing except your self created sounds and recordings. Drop all apps you're currently using with XP. Every app with no exception. Get everything new. If something is still current for Windows 10 and Windows 11, you can download it from the internet, either free or from some webstore. If you cannot find it on the internet, it's gone, forever, and should not be considered for current productive work.
Even if it comes to CD/DVD - forget these as well. Nobody is using DVDs any more, except perhaps the movie industry, and it's dying out. Today, you stream music and movies, and exchange is done as file with USB media, if you don't use web sharing services. No video or audio CD/DVDs.
To become modern, get a Windows 11 PC, get a DAW app, optionally get VST plugins for missing functionality, and create audio files with your creations.