Launcher.jar problem

[57frozen]

i have 32 bit system and installed java 7, the version shown on technicpack.net, but when i downloaded the exe it gave me the could not find java directory error. so i checked common problems and then tried to download the .jar. now the problem is that i have downloaded mods before, so i set .jars to auto open in 7zip. so when i open it it opens the zip file, and i tried opening it with java web start launcher, but it said "unable to launch the application". there was an error message in details, so here it is:

MissingFieldException[ The following required field is missing from the launch file: <jnlp>]

at com.sun.javaws.jnl.XMLFormat.parse(Unknown Source)

at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(Unknown Source)

at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(Unknown Source)

at com.sun.javaws.jnl.LaunchDescFactory.buildDescriptor(Unknown Source)

at com.sun.javaws.Main.launchApp(Unknown Source)

at com.sun.javaws.Main.continueInSecureThread(Unknown Source)

at com.sun.javaws.Main$1.run(Unknown Source)

at java.lang.Thread.run(Unknown Source)

any help would be welcomed, i have technic pack on another computer and it runs fine and i really enjoy it, i would like to do so on this computer as well