I'm happy to report that buying a new upgrade box last month and installing Windows 7 on it went without a hitch. You may be aware that Windows 7 comes in various flavours. I purchased 7 Pro 64bit because of all the older software we use.
So far, everything works a treat and I'm not sure I even needed this version of the operating system. Maybe all the old programs would have worked anyway.
The Windows 7 filing system is a little different and I had some initial difficulty with understanding it. I got around this by ignoring it and building directories just like I always had, content for understanding to filter in slowly.
Along with the new pc and operating system, I changed all of our pc's over to the Google Chrome browser after using the Firefox browser for years. Chrome loads much faster and doesn't interrupt us with all the updates we used to get from Firefox. We haven't used the Internet Explorer browser since about 2002.
For antivirus software, we use Eset's Nod32 and I've had terrific backup from this company. Malwarebytes and Ccleaner are programs I would recommend for keeping the system clean.
As genealogists, understanding our equipment often takes a backseat until something goes wrong. We have accumulated a lot of 'important to us' data and can't really take chances. I don't know about you, but I tend to keep more data online now using google documents and private sites.