December 06, 2011, 02:34:03 pm
Your ATI Radeon HD 4550 gets 353 PassMark points:http://www.videocardbenchmark.net/gpu.php?gpu=Radeon+HD+4550
I'm not sure how this compares to your Intel HD 3000 (and you didn't mention if it has a secondary (faster) graphics card which is controlled by Optimus).
For simple scenes, you can get by with a card that has about 1,500 PassMark points. I say 1,500 to be on the safe side - it really depends on your expectations. Gaieus uses an Nvidia GTX 9800 for example, and he's reasonably happy with the performance, even though it "only" has 1095 PassMark points:http://www.videocardbenchmark.net/high_end_gpus.html
If you want to use Lumion for more complex scenes, you'll need a card with say, at least 2,500 PassMark points (avoid Quadro and FirePro cards).
And very complex scenes would benefit from a card with at least 3,000 PassMark points.
Performance depends very much on the resolution though. If you're only ever going to use Lumion at the native screen resolution of your laptop (for example 1366x768) you will not need as powerful a graphics card as if you were to connect it to an external monitor with a resolution of 1920x1080.