the neopentyl structure is the 2,2-dimethyl propane. The reason the IUPAC name doesn't have 'pentane' in it is because the structure is better described as a propane derivative.
unfortunately, chemistry (particularly organic chemistry) is littered with examples of 'trivial' names which just have to be learnt as needed. while it can be irritating at times, they are often much easier to deal with thsan full IUPAC names!
a useful tool for structure/name interconversion is just chemdraw from ACD. the latest versions (i think from about version five onwards) have autonom which provides this service, as it were. you may just be able to get autonom on it's own, but i'm not sure. chemdraw is great anyway, and any self-respecting chemist should have a copy!
an easy way to find the structure of any compound is simply to google "name + structure". the sigma aldrich website is also handy for this kind of thing, though you won't be able to find more exotic chemicals which they don't sell. THey have recently updated the search engine with a structural search though, which comes in very handy...