I get an error from simply extracting the .rar file with 7zip saying "unexpected end of archive. C:\Users\Owner\Downloads\MGSO_e-_Final.rar CRC failed in 'Data.exe'. File is broken."

I've tried uninstalling morrowind and reinstalling, installing new versions of 7zip, installing different links, and I just can't figure out what to do.

Archive you downloaded is damaged.

Yeah.

In other words, your download either didn't finish correctly, or you downloaded a bad file. Check to see the size of the zip file - if it isn't 1.7 GB or thereabouts, then the download may have prematurely ended for whatever reason.

Edit: Download here, if possible: http://www.moddb.com/mods/morrowind-overhaul-sounds-graphics/downloads/morrowind-overhaul-sounds-graphics Note that the file size should be around 1.7 gigs.