Uh, a CAB file is just a compressed archive, like ZIP, RAR, etc. Any WinZip type of program can decompress it. Freeware ones I use are:
http://www.7-zip.org/http://www.izarc.org/download.htmlIf you have an Ys IV disc, the patching would go something like this:
1) Use TurboRip to dump it to ISO/WAV/CUE.
2) Copy the Ys IV CAB file from my site into the same folder as the ISO/WAV/CUE image file set.
3) Decompress it with one of the programs I mentioned above or any other WinZip clone, etc.
4) Double click the PATCH.bat file.
5) Mount your CUE file with Daemon tools.
6) Run MagicEngine, and use a real System Card 3 to boot the game (not the Magic System cards; avoid those).
That should do it. Alternatively, you have another easier option. MagicEngine can patch on the fly for both Xak III & Ys IV. David Michel, the creator of the emulator, knows me, my projects, etc. and added a feature where the emulator will detect my two PPF files if they're in the same folder as pce.exe. If you load a real Xak III or Ys IV disc, it'll patch the game for you, no CD-R or image file set required! So, you could take your original Ys IV disc, place it in your drive, then copy "YsIV-ISO.ppf" in the same folder as pce.exe and voila! When you start the game, it'll be English. No having to rip the game to disk and physically patching it. However, if you wanna burn a CD-R and play the game in English on real NEC hardware, yeah, you must follow the patching instructions I listed above obviously.