Availability of Hardware Acceleration
GDI is hardware accelerated on Windows XP, and accelerated on Windows 7 when the Desktop Window Manager is running and a WDDM 1.1 driver is in use. Direct2D is hardware accelerated on almost any WDDM driver and regardless of whether DWM is in use. On Vista, GDI will always render on the CPU.
So while Direct2D would obviously be preferred, it definitely seems as if GDI should at least make use of some hardware acceleration once the prerequisites are met. That's why I'm kinda at a loss as to why it's not using the GPU at all.
Looking around some more, it seems only a few GDI features have HW-acceleration in Win7. And obviously not the ones the game is using. So no luck there I guess.
Scratch that, now I'm even more confused. Just read through an article on Tom's Hardware about 2D GDI acceleration and Windows 7, then downloaded their 2D benchmark. Checked it with Dependency Walker and it's using User32 and GDI32 just like the game. Difference is, their benchmark is showing significant GPU acceleration( upwards of 40% depending on which test I run) yet the game is consistently showing 0% GPU usage.