To follow on from Zaine's thread here: -
I think it would be a good idea to consider what we think is a good interface and a model for software interface design.
I think anything based on the standard Windows GUI API's are perfectly acceptable, but as mentioned in the thread above I also think WinAmp is both beautifully crafted and functional. Everything is where it should be and it is simple for a first time novice user whilst being powerful for the weathered power user.
I personally think the key to interface design is having something which looks and feels simple on the surface that also meets the most demanding complexities of any given software.
To me, one of the most perfect interfaces I have ever used was 3D Studio 4 in DOS (and I still occassionally use it to this day). If I can sort out a DOS boot to capture some screen images I'll post them here. Unfortunately I feel they lost the plot somewhat with the complex and confusing interface with later Windows versions.