All 1996 and newer foreign and domestic cars use the same on board diagnostics. OBD II. A code reader and a scan tool are two different things. It sounds to me like a code reader is the way you want to go. I would reccomend this one. http://www.iequus.com/item.asp?cid=7&pid=3110
It will pretty much give you what you are looking for. It will allow you to read erase and give a detailed description of each trouble code found. It will read all 96 and newer vehicles with OBD II, and it is CAN ready which is a new data interface control that many new vehicles are coming out with. In other words it is what allows the many different computers and modules on the same vehicle to communicate with one another. I work for O'Reilly Auto Parts, and we carry this tool, so if we have a store in your area come in and look at it. It is geared and priced for the DIY'er and is very reasonable.
One thing worth noting is that just knowing the code is often not enough, such as if you get an oxygen sensor code indicating a lean condition, don't automatically assume the 02 is bad, it could be a number of other factors. Knowing codes only gives you a place to start looking. If you do end up getting a code reader I would also suggest getting a Chilton's manual for DIY engine diagnostics. They are very helpful in troubleshooting problems and will have a catalog of codes sometimes not found in the code reader literature. Hope this helps you out.