For the same price you could get a desktop with:
- Intel I7 920
- GeForce GTX295
- 6GB of DDR3 memory
- 2 x 500 GB SATAII 7200 RPM hard drives
- A good motherboard that supports everything
- DVD burner
- 800W power supply
- A sweet looking case
Overall, that would give you at least twice the power for the same money. If you just buy parts and build it yourself (which isn't difficult), you can even avoid all the crap with formatting your hard drive violating your variety and you can choose your own operating system. If you're worried about your family using your computer just put a password on it. Even the basic Window password will probably keep them out.
Laptops just aren't for gaming. Sure, you'll have a 17" screen... but COME ON! You can get a sweet 21" or bigger which, believe me, will give you a lot more pleasure gaming.
If you wanna move around and develop for Orbiter, just get an average laptop. That will do the job well and won't cost a fortune.