AMD Radeon has same optimus technology, 3D vision, 3DTV play, FXAA and all.
Even apple iMac, macbook pro comes with radeon technology. Dell said 7730M is better than 640M, so 15R is better than 14R.
You can not use 3D version, unless you have 3DTV or monitor and a pair of glasses, which costs very expensive.
There is nothing specific for college use, its all upto you what you ask your friends. 15.6" is little more bulky but bigger screen and 14" is for compact to use but small to see.
These are not gaming laptops, these are high end entertainment laptops with medium graphics.
It was always affordable last years hp dv6 6121tx was having almost same performance and costs 53k only.
Im sorry sir but dell never said that 7730M is better than 640M ok!, i recently chatted with dell expert and he replied me that the nvidia one will be a better option for gaming as its having more technologies and heats up a comp less and all takes less electricity and can using the optimus technology even boost itself when the cooling system is doing great and the pc is pretty cool. Also according to netbookcheck.net, 640M is a rank ahead of 7730M, take a look at this Mobile Graphics Cards - Benchmark List - Notebookcheck.net Tech and next time dont lie on the forum that dell said amd is better.