Can the Macbook Air 4GB handle Garageband and iMovie video editing?

Hello everyone! I am fairly new to the Mac ecosystem, and not as you may know it. About 6 months ago, I walked into and old pawn shop and purchased an old 2008 Macbook (Early 2008, 2.4 GHz Core 2 Duo, Intel GMA X3100 144MB, 4GB 667 MHz DDR2 RAM, 500GB 5200 RPM HDD from Samsung) because I thought it would be pretty cool to see how an older Macbook would perform in 2015. My results were actually very good! I have been able to edit videos on iMovie, although Garageband can be a bit sluggish and can't handle all that many tracks. Online use is basically seamless, with only the occasional hiccup. Youtube takes less than a second to load and I'm running OS X 10.7.5 on it (Lion). I'm actually using it right now to make this post.

However, having entered college 2 years ago and being a music student, I am into GarageBand (the newer version) and would like to have some fun with my music buddies and maybe have a few sessions. I'm nothing close to being a pro and probably won't use any pro software until I learn how to, at which point I will be ready to purchase a new computer that is more performance oriented. I'm leaning towards the Macbook Air, either 4GB or 8GB RAM (just to keep it safe for the next few years and also, because a performance boost never spares) and would like to know if this is a good option. I will be using a USB condenser microphone and don't mind using the native keyboard to create the tracks. Again, it's all just for the fun. Using this 2008 Macbook has made me understand why Mac's aren't all that much more expensive (and can be cheaper in the long run) than PC's. So, my question is, will the Macbook Air be able to handle this type of use for the next 3-4 years? Any answers are appreciated, even more so if you're using a Macbook Air. Let me know! Thanks and sorry for the long article. Haha!