I might do a little gaming, and potentially run some engineering programs in the future. Any major problems there?
In terms of gaming, you're going to run into trouble.
A MBP 15 i5 with 330m has to run it BF Bad company 2 at the lowest settings while an Envy wiht it's ATI 5830 can run it maxed out at high resolution.
Hopefully Apples switches to ATI cards sooner or later because Nvidia is bad.