PCWorld has a pretty thorough writeup about why and how you should install the new beta of Office 2010. I’ve been running the technical preview and now the beta, and I have to say that it is a worthy upgrade. I agree with the “expert” quoted in the article:
But what does our expert say? “Anyone interested in Office should get a copy of this beta,” wrote Preston Gralla in his first-take review. “It was solid and performed well without crashing once. I experienced none of the slowness that you sometimes do with betas.”