New to Java

I hope I'm putting this in the right area but I'm brand new so apologies in advance.

I'm trying to develop a program to distribute Java to Windows XP workstations using SCCM 2007. I have researched all day and I'm not sure if I have the correct information.

So far it looks like I would experiment using -

<jre>.exe /qn JAVAUPDATE=0 AUTOUPDATE=0 REBOOT=ReallySuppress

However, there are other switches and command arguments I have seen also to experiment with possibly.

Is it necessary to uninstall the previous installed version of Java before running a new installation?

If this is the case, how do I call the Java uninstaller from a CMD?

Any helpful advice much appreciated in advance.