Hi everyone,

This is perhaps old news, but a few days ago I noticed that there was a change in XP compatibility.
The change happened about two years ago, already, but maybe you didn't notice.

Apparently, there was a security hole in the old "VGA" emulation, so VBox switched to two newer ones (one for Windows, one for Linux/*nix).

https://forums.virtualbox.org/viewtopic.php?t=98113

Now, as you may know, 3D support for XP was an experimental feature right from the start.
It was based on WineD3D, the DirectX portion of WINE.
Once installed in safe mode, these system files did handle the DirectX API calls, they got tunneled to the host and drawn through OpenGL.
That way, DirectX worked on any host system VirtualBox ran on.

https://www.nongnu.org/wined3d/

Personally, I used that feature since late 2000s and it worked fine enough for me.

Unfortunately, that 3D feature never left experimental state, so it was not officially supported.

(Bed time story now follows..)

And I assume, by the time Windows 7 came along, another approach was needed, anyway.
At the time, 64-Bit and signed drivers became a thing.
"Hacking" system files, so to say, was nolonger an option, apparently.
Besides, Aero Glass was considered a quality standard by then (business and corporate dudes just loved it) .
Which in turn required WDDM compatible drivers and Shader Model 2.0 or higher.
(Vista shipped with a WDDM 1.0 driver for Geforce 5200 and up.)

As you may know, Directx 10/10.1/11 is/was quite different from the classic DirectX versions (DX7 and before, DX8/9).

"Cap bits" got removed, certain D3D features *had* to be available in silicon, nolonger was a software-renderer around (Win 8.x brought that back, afaik) etc.

The rendering path also changed by using these "modern" WDDM drivers.
Unlike with XPDM, GDI/GDI+ no longer was the driving force and direct frame-buffer access / overlays (incl. DirectDraw) and VGA access for NTVDM fell by the road side.

Windows 7 also introduced the more flexible WDDM 1.1, which brought back 2D acceleration for applications that rely on GDI - it worked on top of of the new DirectX.
Windows 7 also brought us Direct2D, sorta a spiritual successor to DirectDraw - it ran on Direct3D, too.

This is important to note, because there was a change of paradigm after Windows XP.
The graphics cards moved away from dedicated 2D circuitry (Win XP GUI was 2,5D).
The GeForce FX series, for example (5xxx series), was the last one to be based on a hybrid design with dedicated 2D acceleration and 3D acceleration in silicon.

After that, 2D work was done as a side job by the ubiquitous 3D circuitry.
Perhaps we can't blame the industry, because 2D wasn't considered very sexy anymore.
Little did it know how important 2D really was still, at the time.

That's why at the time, even an old S3 ViRGE PCI card could outperform a high-end GPU from the late 2000s.
- When it comes to GDI performance on Windows XP and Vista.
There's an article at Tom's that explains it rather well.

Re: Best PCI VGA card for Windows 3.11 performance?

Anyway, these are just my two cents.
I likely made a few mistakes here and there, but maybe it helps you to get 'the picture' why things ended up like the way they did.

Best wishes,
Jo22