I just bought a copy of Auto Tech from Wal-mart and I do not recommend it at all. It only cost me $10 but it was pretty much trash. What it has is certain symptoms a vehicle may have and you can pretty much pinpoint diagnosis of your vehicles. The problem I found with it was I had a "ticking" noise coming from my engine. I KNEW it was because I overfilled the oil a good bit and finally drained the excess and problem solved. It led me to think that my valves needed to be adjusted which IS a possibility or an exhaust leak another good possibility. Over filling oil can cause piston slapping the oil making a ticking or slapping sound sometimes too so there's one strike for it.
Next: I looked into clicking noise in front in just for the heck of it. Normally indicating a damaged CV joint (duh) it then asks if the vehicle is front wheel drive. I selected "No" and the program said "no diagnosis available since front rear wheel drive vehicles do not have a CV joint". WRONG! Most 4wheel drive vehicles today do have CV joints. Don't waste your money like I did.
One thing I DID like; however, was it has a maintence log you can write in it. Anyone that does their own service records *should* keep a log of maintences.