I am adding a reply to this message mainly to help someone, who would be interested to run NetBSD on the desktop, as I have a lot of experience with running Gnome, Kde and Xfce desktop and with Xen on NetBSD.
1. pkg_add is really unreliable lately. It often freezes in the middle of a transaction, no idea why. The more comfortable option is pkgin in pkgsrc, however even that one tends not to complete the installation. Anyway in both cases there is need to tell the computer where the packages are, and unfortunately that changes. For pkg_add do "export PKG_PATH=ftp://ftp.netbsd.org/pub/path/to/the/packages/" and if you want it permanent put this into /etc/profile, in the latter case edit /etc/pkgin.conf or whatever they decide to call that config in future.
2. using pkgsrc to compile sofware is really more reliable option, however, adjust /etc/mk.conf before compiling the software you want. To see the options you can get, it is advised to go to the software you like and see the options e.g. "cd /usr/pkgsrc/print/gutenprint && make show-options"
3. since the 5x series, I have found NetBSD less and less reliable in terms of applications from pkgsrc crashing without a cause, and NetBSD kernel failing unexpectedly while xen runs
so, if you like testing and adventure, go and install NetBSD, because there is really plenty of packages in PKGSRC and multimedia of all kind from Flash over gstreamer-plugins-bad and ugly to vlc and libdvdcss and they work. Don't expect stability however.
In any case http://wiki-static.aydogan.net/ be your friend where you find a lot of stuff until they fix the original wiki.