It's a bit light on memory, especially if part of that 4GB is covering graphics (i.e., not a discrete/separate graphics card). Since you're using 64-bit Windows, you can add memory, assuming those sticks are available reasonably, and it will get happily gobbled up.
I would skip the W10 upgrade unless this is your only computer and must be up-to-date with all the security updates and stuff. In which case, you probably definitely want to look at adding some RAM.
W10 did not treat my equally old notebook kindly, though I was an early adopter so probably got the most bugs - that system is now running Ubuntu. Your options for DAWs and plugins will be more limited with Linux, and that is not a system I'd put a VM or even Wine on and expect decent performance (but that's me, having worked in the PC industry for 20+ years before retiring).
P.S. I can only speculate, but I'd guess that most folks using older equipment for audio, and are happy with it, are using systems fairly dedicated to just that task, and probably, or typically perhaps, not using the newest versions of software, which is almost always developed on newer hardware, with only a brief concern for compatibility/upgrade use, vs. production use on older platforms.