Looking for the ideal 50cc or 125cc bike, help needed? suggestions?

After considering spending my money on a new tv or the ps3 ive always been after, ive finally settled on buying a scooter/moped/bike. Being a total noob when it comes to these things i am in need of help. What is a good first bike?
After sifting through countless reviews, many terms seem to bewilder me. What is the difference between a 4 stroke and a 2 stroke engine. Please leave ur suggestions and what ur first bike was? Im looking for something in the range of $800 and $2000 dollars, what are my options?

:)