i really wanna whiten my teeth. any comments or info on cost? aftereffects? things like that? thanx a bunch!

I had professional whitening done by my dentist a few years back. This was the kind where they make the trays and then you use a peroxide type of solution at night. It was very effective and the results lasted quite some time.
Fast forward a few years. I decide since I have the trays, I could purchase some of the kits you see in the stores to use in them.
The results were impossible to see, and I sincerely feel I only damaged my enamal on my teeth, because shortly after using this, the pop I have always drank suddenly started eroding the enamal. I always have drank soda, been careful, and brushed teeth. Never a problem. But as soon as my enamal was weakened, it became a big problem.
My advice? It is worth it to have it professionally done!

It must vary from person to person. I just had my teeth laser whitened but was disappointed with the results, especially, since it cost over $500. I'd ask your dentist about the success rate of laser whitening before I'd invest in it. Personally, I found that the at home bleaching trays that I bought, as well as the bleaching trays from the dentist, have worked for me. You just have to stick with it, on a regular basis. All whitening procedures will make your teeth more sensitive, while you are whitening them. Once you stop the whitening process, the sensitivity subides. My teeth, after they were laser whitened, hurt the most then, and, like I said, I wasn't to happy with the results. Ask friends about their experiences, as well as people on this forum. Good luck.