Getting around Cambridge is relatively easy if you are game to take public transportation.  The Red LIne of the "T" has five stops in Cambridge - Kendall Square, home to MIT and many office buildings, Central Square, a bit grittier but up and coming section of town, Harvard Sqaure, home to the namesake university, Porter Sqaure, a more residential section, and Alewife, which is the end of the line and a good place to park a car if you want to explore Cambridge and Boston by T.  There are also a number of bus lines that make traversing Cambridge possible.  Maps and schedules can be found at http://www.mbta.com/. In good weather, Cambridge is also very walkable.

By car, be prepared to bring a map -- Cambridge, like Boston, can be confusing.  Many roads do not run in parallel lines, are one way, etc.  In addition, most parking is resident only, making a car a potential liability.  Metered spaces fill up quickly during busy times, especially around Harvard Square, and garages are expensive and are limitied to a few areas. During the summer months, on Sundays, a large section of Memorial Drive is closed to cars and becomes pedestrian only, so you may have to alter your route accordingly. Overall, public transportation may be a better bet unless you're going off the beaten path.