cannot load nes roms

First off: on a Mac OSXProblem: the emulators I downloaded (Nestopia and Rocknes) will not load the .7z files I am getting off RomUlation.Help please.
And I am probably going to feel stupid once an answer is given.

Try extracting them via 7zip.I think the programs can only load zip or rar files.And if there is an emulator list-point the program to where the roms are held.THE files from romU-the nes in this case-contain more than one file and can't read it.There are several rom hacks with it-you need (if your english) the roms ending with (U) or (E) with a "!" at the end to signifiy that these are the main dumps.

Thats a compression file? :othanks.

the roms are .nes format.I used rockness and after a bit I relaised (deleted the read me's) that it can't read 7zip files-yet it could do zip (if a single file only) and rar...I think.Best just have just one rom extracted and use.And your welcome :)