Multiple JRuby,JDK environments on Windows 7

env JAVA_HOME is needed

declare -x JAVA_HOME="c:\\Program Files (x86)\\Java\\jdk1.6.0_29"

$ jruby -v
jruby 1.6.5 (ruby-1.9.2-p136) (2011-10-25 9dcd388) (Java HotSpot(TM) Client VM 1.6.0_29) [Windows 7-x86-java]

Notice "Java HotSpot(TM) Client VM 1.6.0_29"

gem fails 20111223_0816

On my Windows 7 system I have installed 2 versions of JDK:
/c/Program Files (x86)/Java/jdk1.6.0_29
/c/Program Files (x86)/Java/jdk1.7.0_02
/c/Program Files (x86)/Java/jre6
/c/Program Files (x86)/Java/jre7

And 3 version of JRuby:
/c/Program Files (x86)/jruby-1.6.5
/c/Program Files (x86)/jruby-1.6.6.dev
/c/Program Files (x86)/jruby-1.7.0.dev

I did this to try out different environments:
jruby-1.6.5 / jdk1.6.0_29
jruby-1.6.5 / jdk1.7.0_02
jruby-1.6.6.dev / jdk1.7.0_02
jruby-1.7.0.dev / jdk1.7.0_02

I manually set my PATH with these folders:
c:\Program Files (x86)\Java\jdk1.6.0_29\bin;
c:\Program Files (x86)\jruby-1.6.5\bin;

$ echo $JRUBY_OPTS
--1.9

$ jruby -v
jruby 1.6.5 (ruby-1.9.2-p136) (2011-10-25 9dcd388) (Java HotSpot(TM) Client VM 1.7.0_02) [Windows 7-x86-java]

How can I tell what JDK is being used? Is it "Java HotSpot(TM) Client VM 1.7.0_02"?

I find that the gem command is failing:
$ gem list --remote json

*** REMOTE GEMS ***

ERROR:  While executing gem ... (Gem::RemoteFetcher::FetchError)
    too many connection resets (http://production.s3.rubygems.org/latest_specs.4
.8.gz)