Welcome, and nice set of parts there.
I have a Core 2 Quad running Windows XP, and I like it. It is not "period correct" but it works very well. IMO the actual computing experience is superior to the hardware that was available when Windows XP was current (i.e. the Core 2 is faster, has some quality of life improvements, but still compatible with XP). The quality of life improvements include:
- You can use any modern power supply. I suggest actually using/buying a new one, from a reputable brand, with a good warranty. Or a hand-me-down from a recent modern build, if you have one handy. This tier list is a good reference. Wattage isn't as important as internal quality, and for your system 450W is more than enough. If you can find something affordable in the low wattage end of the Tier A, that would be ideal. I understand you've been burned by power supply failure before and that sucks. Fortunately the Core 2 era hardware isn't expensive stuff (maybe that's its own quality of life benefit!) but losing it to PSU failure would still suck.
- Your motherboard allows you to use SATA hard drives and SSDs without IDE adapters. Windows XP on an SSD is hilariously fast and a joy to use (not period correct). This is a great use case for smaller SSDs (maybe under 100 GB) that would be too small for a modern system. Most people feel that TRIM (not natively supported by XP) isn't necessary, but if you want to play it really safe there are older Intel SSDs that support manual TRIM in XP via Intel's SSD toolbox software.
- The system still supports newer operating systems such as Windows 10 x64. So there are opportunities to dual/triple boot if that's what you're interested in. This system running Linux would be a perfectly satisfactory daily driver for light computing tasks.
- This hardware is fast enough to run DOSbox at fullspeed for basically everything DOSbox supports. Obviously this isn't a truly authentic way to play DOS games. But this could be a nice thing if your XP machine has a monitor that works well with 4:3 aspect ratio while your Ryzen system doesn't.
If you are installing Windows XP onto a SATA drive in AHCI mode (set in the BIOS) you will need some tricks to get the appropriate AHCI drivers loaded prior to XP setup. Also if you are trying to install Windows XP from a USB flash drive (instead of optical media) some other tricks are required to get it to work. There are several valid approaches to this... I personally use WinSetupFromUSB with an XP ISO slipstreamed with a pile of drivers.
IMO the joy of an XP gaming machine is for early XP era games that use 4:3 aspect ratio, support hardware accelerated sound (typically EAX), or have issues with later 64-bit editions of Windows. Later XP era games will tend to work fine or possibly better on newer hardware (eg your Ryzen system). So for early XP era games your GTX 560 will be excellent. I could also add that a lot of Windows 98 era games can work in XP with some tweaking/patches (not ideal, but way more feasible than trying to get Win9x games running in Windows 10/11).
I happen to have a motherboard with the SupremeFX sound. It "works" but my experience is that I cannot get Creative EAX support anymore (it requires an online registration for a license that Creative no longer offers). As stated above, in my opinion a key benefit of an XP system is EAX. A Sound Blaster Live, Audigy, or X-Fi card would be superior. Even the relatively lousy "Audigy SE/LS" (which uses software EAX) would be acceptable because your CPU is overpowered for the target era of games. Avoid the newer X-Fi cards which are not XP compatible.
For Windows XP, which is a 32-bit OS (XP x64 is another story), 4GB of memory is all you need. You could remove two of those sticks for possible improvements in overclocking stability, or to use elsewhere. If you are multi-booting with a 64-bit OS you can keep all the memory installed - XP will still boot fine (it will just ignore the extra memory it can't use).
And lastly... people on the internet don't get to decide if your build has style, soul, rhyme or reason. You do! I hope you enjoy the build, and the hobby!