As I understand it PUR filters on the faucet take out tons of stuff because they're activated charcol. Read their package. It says there. Weather or not you trust that is up to you. ;)
Reverse osmosis is supposedly really bad. It wastes sumthin like 50 gallons for every one gallon of water made. PLUS it could be worse for you since the membrane filter the water is squeezed threw may be years old {never cleaned} and just a breading ground for bacteria which eventually eat holes in the osmosis membrane. Then letting *everything* through in the end. {Really, I read about this somewhere...} Make sure your water dealer reg. cleans the membrane/filter.
Best bet is to order water service from somebody in the yellow pages. You get a water stand and it costs less than $20 a month. Besides, don't we all just LOVE that water cooler water better? :))))) It's worth it in the end.