Speed and memory
In our performance index the Radeon X1800 scores 0.5 and the Intel HD Graphics 2500 (integrated) scores 0.4, which makes the Radeon X1800 about 25% 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 Red Dead Redemption 2 (3 against 2 fps), and the smallest is in Grand Theft Auto V Legacy (10 against 9 fps). Games that are light enough to run above 200 fps on both cards show little difference at all.