CPU
There could be 2 major players here, AMD and Intel, the latter being more expensive. The processor's GHz determines its speed. Even for just home users or students, getting not less than an Intel Core Duo or its AMD equivalent is the best.
RAM
With the features of current OS, all PCs should have best laptops under 100 at least 2 GB of RAM. This determines the speed of your computer to react on commands. Commands can be as simple as opening or saving a document. If you are to use the computer mainly for internet, word processing and some spreadsheet creation from time to time then you do not need a very high RAM.
Video Card
A powerful video card is not necessary unless the laptop is to be used for video editing, gaming and the likes.