I know arial is but is arial narrow? It look pretty good in here: http://www.paessler.com/tools Though never used it myself. The most web safe fonts list I came across didn't include arial narrow. Doesn't it mean it's not web safe?
Nope, its not (as in, you can't be positive it wil be installed in all browsers). if you're feeling adventurous you could take a look to the @font-face css3 property. But that's not "safe" either as it is not 100% supported yet (mostly because of IE) also, when declaring font-family on recular CSS2 you can declare more than ona font, use Arial Narrow as your prefered and some other web safe font as your fallback. Remember that as part of the CSS spec you must provide sans-serif as the final alternative