GDocs vs. ThinkFree vs. Zoho vs. MS Office

CWmike writes "Web-based productivity suites, once almost a contradiction in terms, have become real challengers to desktop applications. Google Docs, ThinkFree, and Zoho, have all made major improvements in recent months. They're becoming both broader, with more applications, and deeper, with more features and functionality in existing apps. The question is: Are these three applications really ready to take on a desktop-based heavy hitter like Microsoft Office?"