It would be very nice to obtain that kind of information and still rely on it as it is in reality.
Usually Pantone colours can only be seen on their official catalogues, as colours on digital surfaces tend to be converted to the screen crystal cells format.
Anyway, you've even got a comparison tool on their site I think, but my advice as a Designer is not to rely on those colours, as a simple tweak on a colour can sometimes ruin hours of work.
Here is a simples site I found: http://www.ginifab.com/feeds/pms/cmyk_to_pantone.php
Good Luck ;)