Being a bit of a Mac zealot, there is nothing I find quite as irritating as a Windows zealot. His pro-Windows argument is always two-pronged: price and the number of software titles.
The price question is ignorance, but the software title point is correct. Of course, when pressed, you will find that most Windows users make little use of this supposedly vast software title advantage.
They use Netscape or Internet Explorer, a few games and Microsoft Office. Microsoft Office in particular has become a de facto standard.
With the possible exception of Mirabilis' rather anaemic implementation of ICQ, as a Mac user I have never really felt the effects of any software disadvantage.
However, after installing StarOffice 5.1 on my Windows machine, I did feel a twinge of jealousy. StarOffice is available for Linux, Solaris, Windows and even OS/2, but not for the Mac.
Recently acquired by Sun Microsystems, StarOffice is not the most petite office suite I have ever seen.