Help, I need to buy a torque wrench

Very good points guys! The old beam wrenches are only as accurate as the user. The same with the dial wrenches. They are the most accurite but you have to be looking straight at the dial when you pull. For engine assembly I prefer the clicker type. They are accurate to usually 2-3% which amounts to a couple ft/lb when torquing at 100#. The micrometer style clickers (the ones you have to screw the handle to adjust the torque) are more accurate than the split beam wrenches by a percent or two. (The old Snap On wrenches made by Precision Instruments that adjust with a flip lever and a adjustable knob on the side) THe big difference in the two clickers is the micrometer wrenches will loose their calibration easier and should be backed off when not used. The split beam wrenches use a tuning fork design and don't need to be backed off and seem to stay calibrated longer.
The new digital wrenches seem to be the best of both worlds but there again are only as accurate as the user. Different size wrenches are for the torque values you require. Engine builders usually have at least a 3/8" drive ft/lb. that torques in the 10-80# range and a 1/2'' drive that goes up to 150# Most new car engines require you to have a in/lb. wrench for small fasteners and they are usually 1/4" drive. A dial wrench can be used to check things like rolling torque on pinion bearings when setting up rear ends and the like. I can't help but think that the more expensive wrenches will be a better product but it's hard to justify the price if you are just using it once or once a year. I hope this helps.
toolmanmike