Sounds like you learned the hold a normal breath and float at eye level with no air in your BC technique. If you do it at the beginning of a dive you will be pretty close, and will get through the dive alright but if you do it with a near empty bottle you will be closer. Aluminum 80 tanks change buoyancy by roughly 4 lbs at the end of a dive due to gas used. You can also find neutral with a full tank then add 4 pounds. That is assuming you are using an aluminum tank every kind of tank is a little different.
The big concern about being buoyant at the end of a dive is that you will not be able to ascend in a slow controlled manner. Also, if in the extreme case you had to make a decompression stop you want to not float uncontrollably past that stop. In that case it could mean your life. Another scenario is you are surfacing and notice boat traffic overhead. If you can not control your buoyancy there may be a boat prop or a jet ski with your name on it. Buoyancy is a skill that takes practice, and anytime you change gear, body weight; etc. it changes. But in the interest of reef preservation and personal safety it is a noble pursuit. I am glad to see you guys are after that goal.
Cheetah you might consider a Peak Performance Buoyancy class or other further training i.e. Advanced Course. Either one will allow you to try things out and have an instructor handy for advice even if it is a question about something covered in other courses than the one you are taking . Plus advanced classes are just plain fun. They usually consist of more dives than book work. They will give you lots of experience in different kinds of diving too. Advanced classes are my favorite ones to teach. Diver skills and confidence really blossom in a short time in those classes. It is fun to watch and participate in.
Happy diving!
corrections 5/28/06:
add 5 lbs when using aluminum 80 not 4;
it is safer to be a little over weighted than under weighted, and one can adjust for the overweighting with the use of their BC with the trade off of higher air consumption;
see Markfm's posting, my second posting on the subject, PADI's Adventures in Diving, PADI's The Encyclopedia of Recreational Diving, and the appropriate text from all training agencies for a more in depth discussion on propper weighting.