Edit:Just discovered that "Windowed" mode plays fine on the Celeron/Intel HD2000 machine(solid 20-24fps @ the default resolution of 854x480), I can now confirm that the game plays okay even maximized in windowed mode, but when hitting F11 to go full screen mode, the performance is abysmal. Hitting F11 again to go back windowed and performance returns to an acceptable/playable level.

I don't see the same performance hit on my Geforce GTX 550ti machine(specs listed in below paragraphs) when hitting F11 to toggle between fullscreen and windowed mode. The performance on it stays the same. So, I think this is related to the Intel Integrated chipset/drivers in some kind of way. Full screen mode is terrible, on the Intel Celeron/HD2000 machine, as described below.

The game simply runs terrible. FPS constantly is in the 1-10FPS range. No amount of tweaking in the video settings helps the performance. Mostly stays in the 5-8fps range. Staying still in the game brings up the fps a little to the 18fps range, but as soon as I start to move, fps dips, lags slows down, simply unplayable. All of this is in single player survival mode. The desktop resolution is 720p scaled to 60 percent in the intel options for a Panasonic 42" tv.

I have another system with an AMD Athlon x2 3800+ 2Ghz, 2GB RAM, Geforce GTX 550ti, Windows XP. The game runs at a good 35-75fps and never dips below 30fps(full screen, the desktop resolution is 1280x1024). I have benchmarked both CPU's and the Celeron outperforms the old Athlon x2 3800+ 2Ghz. So I think that leaves something going on with accessing the GPU. I don't have the talent to figure out where the problem is located, but I think this game should not be performing this poorly even with "Intel HD2000 Graphics". May not be an apples to apples comparison, but Quakelive runs 50-75fps on this Celeron machine.