I'm trying to build software so I can get KDE4 on my Mac. But MacPorts seems to constantly try and use GCC-4.0.1. Is there a way to get it to use GCC-4.2.1 that comes with XCode? Or GCC-4.4.0 at my option?

My suggestion: let macports do what it does. It will compile everything for you so there is no need to specify using 4.2. It will be used when necessary if you're on leopard. If you're using tiger, things get more ... involved

Yeah, from what I read from the internet that gcc-4.0.1 is only useful if you want to make it universal else use gcc-4.2.1. Yeah I have Leopard 10.5.6.