Yep I'd would recommend installing Java 1st. Don't install Java over the net but from your HDD: Java 1.5 (take the JRE)

Likewise for LW, download the LW installer & SAVE it to your HDD. Then install it. Make sure there's no other programs running during the installation process. In fact, I rebooted after downlding it & before installing LW. Although the site says it's LW 4.6 it is actually 4.8.

If you still have problems then there is an alternative installer I think. You just unzip it & use it. See Here about other version. If still problems after that then do a registry clean: some choices ones if you don't have a registry cleaner