The Namco Museum PS games are just compilations of older games, mostly from the 80s and early 90s, and the soundtracks to most of those games are in the "Game Sound Museum Namcot Edition~" box. I don’t really know the games, but if the soundtracks remained the same in those ports, you will find most of them in the link I sent.
Well, the last option that i can think of is the .psf files. They are perfect, because they contain all the music in a really small file, but need special players. Also, you can rip WAV files from it and make your own soundtrack. Zophar’s Domain have all the Namco Museum games, I checked it. Well, that’s my final comment. Wish you luck.