My 2 cents:

I don't think large Excell files are good. I ran into one person at work who couldn't do a mail merge with Word because the table she was trying to use had over 3100 rows and columns out to BT. Guess what, it doesn't work!

But I do agree with Bruno that I have yet to find something to replace MS Office (sadly). Openoffice isn't exactly a joy to use. Abiword isn't too bad, but also not great.