is there one? i mean the original score by inon zur. i've searched all over, but the most i could find that was released was a sampler cd with only 2 tracks by zur. surely he composed more than that for the game...

I'm pretty sure there isn't one.
There's loads of rips all over the Interwebs though.

Quick update as I'm checking Fallout threads while listening to the excellent Fallout 76 soundtrack - there's a Fallout 3 OST digital edition as well as several out-of-print vinyl editions.

Fallout 3 Original Game Soundtrack (digital): https://vgmdb.net/album/37621
Other Fallout 3 soundtracks: https://vgmdb.net/product/4246