I have modded oblivion before and know that .esm can be opened with some method, perhaps it is the same for both games. I was wondering if anyone knows the softwear to do this so i can access files in an .esm i have downloaded.
Thank you

A .esm is not an archive. There are no files inside of it.

Yea the esm can be viewed in the GECK, but it just tells the game what everthing is. Any actual files that go with the esm would have been downloaded with it.

BSA != ESM

esm is masterfile, can be viewed in geck but not changed. not neccesarely needed to add a esp with it for gameplay. some mod's have only bsa and esm.
however if you want parts of it used in another mod then you can copy/rename them into a new esp.
remember that this esp is always depending on the esm. so if you don't have plans for major changings i suggest to not make parts of it in a esp. it would only result in another mod loaded.