Which Java version to use as administrator

Hello all,

Probably this question is silly, but I'm facing many problems working with Java and the different products related to my tasks as sysadmin. In my PC I need java 1.4.2.12 to be installed for Download Manager (with other versions it simply doesn't work), but I also need version 6 so as to access the different functions in SAP PI 7.10.

I have tried using Java Web Start to deactivate the version I don't need at a certain moment, but I had no success and I still have problems. Right now I had to de-install Java6 so as to download a SP Stack.

How are you dealing with this problem?

Thanks and Regards

Francisco