What is "antivirus"? I thought you were using a Mac!
Seriously, I've not found anything that has ever found a virus, even a PC one, on any Mac. They are somewhat of a "big hammer" at any rate; they often cause more problems than they solve, at least on a Mac running the latest OS. They almost all depend on libraries of known malware/virus codes. But as soon as they are updated (a new virus is detected and announced), the hackers change the coding enough to bypass the 'detector'. Of course, they 'detector' is still useful for watching for files that may come in an email that you forward to another windows user who doesn't use any antivirus s/w. I suppose that group will never cover all windows users.
I think most people eventually find they should be turned off when making downloads from
trusted sites. I still always end up returning to ClamXav and run it on start up.
Of course, even Mr. Tessler reported extremely long download and install times on the first day. Too many trying to access the code at the same time. Secondly, the "Installer" only installs itself. The real traffic occurs when the Installer starts downloading the actual OS, a much larger file.
Glad to hear things finally went smoothly and at a reasonable speed!
Have you discovered any "must-have" features? Have you tried "QuickType"?