IzPack should work everywhere. However, you have to be aware about several things if you have support for 64bit machines.
First, if you are using COI tools from IzPack (for example if you have your own custom panel that works with registry or using CheckedHelloPanel) you also have to deliver 64bit dll:
<native type="3rdparty" name="COIOSHelper.dll" stage="both"> <os family="windows" /> </native> <native type="3rdparty" name="COIOSHelper_x64.dll" stage="both"> <os family="windows" /> </native>
The second thing, if you are using ShortcutPanel, you will also have to deliver 64bit dlls:
<native type="izpack" name="ShellLink.dll"> <os family="windows" /> </native> <native type="izpack" name="ShellLink_x64.dll"> <os family="windows" /> </native>