Creating heavily customized windows installers?

I'm having a product which is currently using 2-phase installation:

1. WiX-based installer to copy the files and create the shortcuts
2. Custom application to do all other required actions like checking prerequisites, updating/creating database开发者_如何学C, contacting some 3rd-party web-services to make sure we're running on "good" machine, and so forth.

What I need to do is to implement a single-phase installer, that does all the neccessary actions at once, without running any external applications.

I've already tried to use "custom actions" to display my custom wizard at some moments of installation process, but it looks terrible. I've also tried implementing custom steps in WiX, but it's too complicated to maintain and not make any mistakes.

What I'm looking for is a kind of framework that allows building MSI files that are heavily customized with .NET-based functionality (like custom .NET controls and other things of that kind). The second major requirement is ability to easily decide what are the next steps for installation wizard depending on current context.

That would be great if this framework is free for commercial use, but I'd also be grateful for non-free solutions.

MSI doesn't support mixing its UI with custom controls. You can replace MSI UI with an entirely .NET UI (WPF or WinForms) using EmbeddedUI or a Burn managed bootstrapper application.

Take a look at NSIS. It has a kind of scripting language and plugins that allow you to create very complicated installation scenarios. But it does take some time to learn.