Andrew, I think you are jumping to damaging conclusions here.  There is no
evidence that I can see to connect Jack East with the "Jack" who was behaving
questionably earlier, and some considerable evidence to suggest that they are
two unconnected people (in different continents).

One thing that you may not know is that -- at least until fairly recently, and
at least at some schools -- Chinese students were taught that it was a good
idea to adopt a Western name when dealing with English speaking Westerners.  I
don't know where that idea came from, and I don't think it's a very good idea
myself, but it explains why there are quite a lot of obviously non-English
posters using very English names on these newgroups.  There is no intent to
deceive, they are just trying to fit in in the way they've been taught that
"we" prefer.

Anyway, to get to Jack's question (finally ;-).  I can't personally recommend
any specific Zip software.  I used to use  ZipCentral and was reasonably happy
with that.  But I don't think it exists any more.  Recent versions of Windows
have Zip en/decoding built-in.  That's not a particularly good or general
implementation, but it is sufficient for checking the contents of JAR files --
you just have to copy or rename the xxx.jar to xxx.zip.  If you need more
detailed information about what's in a Zip/Jar file than that (e.g. checking
for format errors) then you might try the "zipinfo" program that comes with
Cygwin, although I doubt if you'd want to download and install all of Cygwin (a
Unix environment emulation for Windows) just for that.  I should add that
pkware (who invented the ZIP format)
       www.pkware.com
have some free and trial tools although I've never used them myself.

   -- chris

If Java has installed itself correctly on Windows, then double-clicking a JAR
file will attempt to start
   java -jar <filename>
which is /not/ what you want...

   -- chris