Java HotSpot Virtual Machine

Hi

I have a bit of a catch22 situation that I hope someone can help resolve.

I currently have JDK 1.5 running on my PC along with netbeans 5.5, everything with netbeans is OK.

I also have iReport 1.2.7 running and it is also fine......up to a point. The problem is that if you have JDK 5 installed then iReport will only compile reports that do not contain an embedded scriptlet, any report containing a scriptlet will result in an error when attempting to compile. (The error is due to an incompatible version of rt.jar...49 instead of 48).

iReport will only compile these reports with JDK 1.4.2. The problem is that even with JDK 1.4.2 installed alongside JDK 1.5 iReport always finds the latest version.

My question is this:
How can I compel iReport to use JDK 1.4.2 even if there is a later version on the PC?

Many thanks if you can help
GB