I would try a few on your Win98 machine, you might be surprised. Dark Forces 2 modding was strong for many years, there have been unofficial patches to JK.exe which added additional functionality like ‘increased limits for things/vertices/lines/sectors, and allow textures sizes greater than 256x256’. I think the actual number of MOD projects that took advantage of these patches were small, it was mostly utilized in later Multiplayer Maps. Your XP machine should handle everything great. I remember the 7950GT was widely regarded as the best card for DF2, since later cards didn’t support 16bit dithering and ended up looking worse.