Yep go to where surebet posted for more specific information relating to exactly what you're searching for.
It doesn't mean that you can't do both (I sometimes do). It's actually quite fun to buy a .177 and just plink pop cans or paper targets. However I would never dream of even bringing a .177 even remotely close to an airsoft/paintball field.
If you don't want the "FPS drop" that running out of CO2 gives you, you could always go with a compressed air pellet gun, something as simple as a cheap $120 one from Canadian tire. Hell for $50 you could even get a Daisy that you cock the pistol grip (or some other lever) and it compresses the air http://www.dlairgun.com/Daisy-Air-Rifles.html
OR if you're serious about target shooting check these ones out: http://www.targetshootingproducts.co...6ce23c795e592c