Trying to get SSAA with downsampling to native PSP resolution on PC

[Dukatti]

clapclapclap,
to access resolutions below 640x480:

1. Choose & apply 640x480
2. Recheck available resolutions in standard Windows screen settings.
[maybe they firstly should be created before applying instruction steps?]

And there is also an alternative method in case if you are able to change resolution through AMD/Nvidia/Intel control panel:
1. Create desired resolution using Control Panel
[maybe resolution should be deleted from another tools before creating?]
2. Change to it in that Control Panel as well

If everything fails - you can create any 480p resolution, like 848x480 and so on.

anyway - good luck in your experiments!