If you are already running an earlier version of Office, be careful when installing MS Office Home & Student 2010 and read all the information on the installation dialog boxes. I was already running Office Professional 2007 and wanted to install Office H&S 2010, to run alongside it, not as an upgrade that overwrites the existing programs.
It takes quite a long time to install what, on the face of it, is 4 programs, but in reality is all the programs in Office Professional 2010. The additional programs are trial versions which you can convert to full versions by buying the appropriate overpriced Product Key. The problem is that you cannot have two Microsoft Outlooks running together and I found that my Outlook 2007 had been replaced by a trial version of Outlook 2010 which, if I had kept it, I would have had to pay for at the end of the trial period. I did a System Restore to get rid of Office H&S 2010 and re-installed it. This second time, I noticed that the Customize dialog box has 4 tabs and, although on the first tab you can select to keep previous versions of Office, you need to go to the second tab to instruct it not to install Outlook 2010 and any other of the trial programs you don't want.
Why is it that so many things these days have a catch? I can find no information on the packaging or in the Quick Start leaflet in the box that the entire Office Professional 2010 suite would be installed.
I haven't yet had time to make a full comparison of Excel, Word and PowerPoint 2010 v 2007 (I'm not interested in OneNote) but initial impressions are that the tweaks are minor and that, if you're happy with Office 2007, you probably don't need to waste your cash on Office 2010.