7200 vs 5400: this is the speed the hard drive spins at. the hard drive stores data. A 7200 rpm will perform better but consume more power. Personally, I don't think the increase to 7200 is worth it. Especially since the only thing it will affect is game loading times... and only marginally.
That is an excellent GPU for a laptop. You'll do more than fine with it. Here:http://www.notebookcheck.net/NVIDIA-GeForce-GT-330M.22437.0.html
Of course you will have to lower some settings in newer games especially but that's expected with a laptop.
GDDR3 is the graphics memory. GDDR2<GDDR3<GDDR4 etc. It does not affect performance nearly as much as the actual chip (ie GT330M) but the memory type will make a slight difference. Don't worry about it. GDDR3 is good.
Need anything else, just let me know.