Ok so I am getting a new computor in a few hours and I have always been interested in making machinima or gameplay/commentary videos(maybe even joining the video department? we'll see). I know very very little on computors except for the keyboard types and the mouse clicks XD. So my question is what would I need to make these videos? I do believe I would need a capture card to get the videos from my tv to my computor?(correct me if I'm wrong) Although i'm not sure because halo has the theater system, if someone could help clarify that for me. But for Gears, Skyrim, etc... I think I would definately need one. Also would I need video editing software? does itcome with a capture card? And I guess my final question is what is a good model/brand of capture card that is at an affordable price?

So here are the questions I need answered:
-What do I need to make the videos?(capture card, video editing software?)
-Is it possible to get Halo clips onto my computor without a card? (via theater & bungie.net)
-Does video editing software come with a capture card?
-What is a good, affordable model/brand of capture card?
-Would it come with audio editing software too to make the commentary?
-what would I need for audio?
-How much memory is required for this? (the comp i'm looking at has 340GB + I have a 500GB external hard drive already)