I use this site for the netscape skins.
http://themes.mozdev.org/
Any of the ones listed here for mozilla seem to work in Netscape 7.1 also. If you need any help getting them to work let me know. Not that you will, it's just when I first did it, took me a bit to figure out where to put them so they would work. Netscape is the only browser I use if I can. Hope that gives you a little help for what you want to do.
