Ah right well if it states it can do 1080 i, Interlaced mode then fine.
You should be able to get that resolution via the 15 pin D-sub.
The thing is in reality it says 1080 i because it uses what we call scan line switching.
The picture generated rapidly switches from the odd an even line numbers of the image or source you display.
Full True 1080p Should run at a refresh rate of 60 Hz.
But when in interlaced mode the Hz of the signal is halved to about 29Hz for switching between the odd and even scan lines.
That results in slight flickering that can be seen.
As long as you have a decent new graphics card, or new laptop then you should be able to get the quoted 1080 i resolution from the 15 pin D sub connector.