Ahh yes a rookie we have here well first off welcome to "OS...Da Spot" bro now lets see you've got the card working thats a good thing now about the Microsoft cards they are designed to work and are combatable with the AR a match made in heaven with just enough sugar as to not be too sweet.
They can be found at most electonic stores that cater to selling software and XBOX,ps2 and or any other product related to pc and video game products cost about 25-30 bucks I believe and theres always something on ebay and simular sites cheaper but buyer beware you get what you pay for so its up to you!!!
Tranfering to the XBOX via is a simple process...just DL'd files to you card via the AR device you'll see this on the on screen table thats has your files remove it from your docking port and insert back into your controller and DL'd into the game you're using or as some of us vets do DL'd straight onto the XBOX Hardrive itself some files such as MVP baseball will not DL'd from the card direct and you'll need to do this in order to get it to load into the game itself there are other games that require you to do this but later for that.
All files DL'd via the AR can be saved onto your pc data base I save most of mine there because you never know when you'll want to play any outdated game no longer in circulation on the boards lots of mine are treasures that are no longer available not even from codejunkies themselves so save all you cherish into you pc data base you never know when you'll pull it up in the future.
I'm not sure I'm understanding you making a file on your computer,once its in your pc data base it is on your computer and you can drag that file onto your desk top and open or play with files anyway you want but as far as that you save in the pc data base which is basically the same thing and of course you can make copies and put them in files you create which isn't a bad idea once again thats a good thing but if space is a problem then just store it in the pc data base on the AR ,simply drag the file into the center where it says its at....best to also read the instructions that come with the AR to be sure you're following the right procedures.
Other then that you should be fine if you run into any problems just post and I'm sure someone here will assist you if they can again welcome to"OS...Da Spot"!!!
Holla Back y'all