InstallAware

How can I disable Next in the Destination dialog if the remaining space is negative?

Also, I have static text on the form which should display if the remaining space is negative, how can this be done?

Also, I need to dislay all values (e.g. TotalRequiredSpace and RemainingSpace) in MegaByte, how can this be done?

This should be possible. I'll research it and get back to you.

The last point is very interesting for me, too

I'm still researching something, but the basic idea I have to work around this is to create two separate dialogs, one with the button enabled, one with it disabled.

You should be able to perform the necessary calculations to determine what to display using Get Component Space and Mathematics commands. The Mathematics would allow you to recalculate the space into Megabytes as well.