Lilian,
Being late to the party, I hope some advice may help you since unless you graduated in December; you probably havent made a decision. You have asked a great question for which there is no easy answer. The first question you have to answer for yourself will guide your other decisions as you have many fine choices in your price range. That question is what do you want to accomplish with your first quality watch? Do you want something most would recognize as a quality watch or do you want to fly under the radar and have the average person on the street never heard of or appreciate your timepiece? How conservative are you? Do you want a versatile watch or a very dressy watch? This will guide your decision. My advice would be versatile depending on how you answered question #1. If you want the watch a neophyte layman will notice and impress the greatest amount of people, you should get a Rolex of some kind (I would recommend all steel) such as a submariner, explorer, day-date, GMTII or sea dweller in that order (again, get what you like of these, not my preference). Just do not get an air-king. After that, I would recommend an Omega, Breitling or Longines in that type of watch.
If you want a watch that will really fly under the radar, I would take a close look at the Jaeger LeCoultre Master control watches (very conservative) as mentioned by others or possibly a Ulysse Nardin. There are some other great watches that I would place in that category but most will be above your 5k cutoff. Some other choices include Audemars Piquet Royal Oak, Vacheron Constantin or Patek Phillipe if you are willing to spend more (in some cases, much more). Browse online to see your choices, then look in person.
The good news is there are no wrong choices. Pick what fits your personality and your goals. Then enjoy it and wear it and you will notice you will have a quiet inner pride in the fact you wear a 5k+ watch that only 1 in 1000 people will even recognize (depending on your choice). Best of luck.
[FONT="]Bill[/FONT]