Speed and memory
In our performance index the Radeon X1900 scores 0.7 and the Intel HD Graphics 4000 (integrated) scores 0.6, which makes the Radeon X1900 about 17% faster. That is a visible but modest gap, usually 5 to 10 fps in a game that runs at 60.
Both cards have shared GB of video memory, so memory will not separate them.
In our estimates for popular games at 1080p on High, the biggest gap is in Cyberpunk 2077 (3 against 2 fps), and the smallest is in Fortnite (10 against 9 fps). Games that are light enough to run above 200 fps on both cards show little difference at all.