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.
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.