Right, how many of those applications are used on a daily basis by the average user? Visual studio and Active Directory may be the only applications from that list that stand out, but let's look at what the real average users uses on a daily basis:
Web browser - The FOSS solutions are clearly way superior here. I doubt there's any argument about this.
Office - On 99% of the cases you're covered by OpenOffice. Some might say it's not as pretty/lacks features/etc. I have yet to see someone complain that they're not able to do their job with it.
Mail client - Most people have already switched to web clients. For corporate users some might still use Outlook, but in my professional experience most don't use its enterprise features, so they might as well use Thunderbird or any other client.
Music player - Considering most users take the default the OS offers, I'd say even the worst media player on Linux is better to WMP.
If you use SQL Server of Visual Studio for your daily work you're smart enough and knowledgeable to make the appropiate choice for a system (supposedly). But SQL Server is on the same class as Postgres and DB2 for most tasks.
Besider, there's no way in hell you're running Visual Studio, Outlook, or SQL Server or a netbook unless you're into masochism.