The answer to your question depends on your intended use. We are talking about quality products in all the possibilities. Unless you require a spreadsheet with some on the unique capabilities of Excel in some of the most sophisticated (and seldom, if ever, used by the vast majority of users), I see no reason not to use OpenOffice 2. In my opinion, the combination of cost (zero), quality, ease of use and community support is hard to beat. And it also has some unique capabilities, like direct export to PDF and Flash, not available in MS Office.