I'm sorry, but the GMA 950 is nowhere near as good as the Radeon 9550 that was in the last iBook or even the Radeon 9200.
I have the same MacBook as you do in your sig, just with 2.5GB of RAM instead of 3. I've also owned systems with the Radeon 9200 and 9550.
The only thing the GMA 950 has over the 9200 is that the GMA supports Pixel Shader 2.0, while the 9200 only supports 1.4.
The GMA 950 does not support hardware T&L, while the 9200 does. The GMA X3100 supports hardware T&L, but the performance is so terrible that you see people on PC related forums coming up with all kinds of creative ways to disable it so the performance is at least as good as the GMA 950!
Do some googling. You'll quickly find that both the 9200 and 9550 are rated WELL above any integrated GPU out there today, still.
My own experience, I had the Radeon 9550 in a Celeron based system. It was basically 1.2GHz Coppermine based Celeron (overclocked from 1.1GHz), 256MB of RAM, and the Radeon 9550. I was able to push UT2k4 and HL2 at full details at 1024x768 and still get around 40fps. My MacBook can't even choke out 30fps at 800x600 with medium settings.
The GMA 950 and X3100 are simply pathetic.
Intel's integrated graphics are not good for anything. They offer no advanced video features like nVidia and ATI/AMD's integrated chipsets, their 3D performance is terrible.. Their DVD playback performance isn't even as good as desktop GPUs from nearly a decade ago! They're a joke. Look at my GeForce 8400M GS in my HP. It does full decoding of every video format, full hardware deinterlacing, deblocking, etc. It can play blu-ray discs without a sweat. The GMA 950? Even in Windows (since OS X does not take advantage of GPU features for video playback), CPU use is unnecessarily high because the GPU can't do anything for video playback.
The MacBook Pro isn't suited for "heavy 3D work" either. The GeForce 8600M GT it has is at the bottom of the "mid-range" cards currently available. A $2,000, $2,500, and $2,800 computer should come with no less than a GeForce 8800M GTX.
If Macs were priced like PCs, the entry level MacBook would have a DVD writer, 2GB of RAM, and a GeForce 8400M GS. The middle would have the 256MB GeForce 8600M GT. The black would have the 512MB version. The MBP would have the 8800M GTX 512 at $2,000. Dual at $2,500 with 1GB of memory and same for the 17".