Do you have an external floppy drive? That's the $64,000 question!
If you do, then yes, you should be able to open those old Word docs using Word 5.1. However, it would appear possible that AbiWord only supports Word 6.0 and newer - I can't find anything about it on their web site, but have found a couple of very old discussions. The file format for Word 5 and Word 6 are quite different, so it may prove problematic. If you were using OS 10.3.x, you'd be able to open them using TextEdit too, but I don't think the version you have can do it. OS 10.3 is pretty cheap (about $50 from various dealers) - if those Word files are really important, this might be the answer. Might be worth it to send someone running 10.3.9 one of the files via email first though, to make sure it works.