Lost MS Office, can't open in iWork

So recently I had to re-install Lion, and lost a bunch of applications. I no longer have the disc for MS Office. I have a number of Work and Excel documents that's I can't open. I've tried opening in Pages and Numbers, but keep getting an error message. "Numbers quit unexpectedly while using the SFCompatibility plug-in" Since I can't open the documents, I can't tell them to open in the iWork application. Any way I can get these documents open without having to buy MS Office?