ORIGINAL ANSWER:
It depends on the game and whether or not you download add-ons and such. but it should hold like 30-40 games on average.
ADDITIONAL INFORMATION:
If you want a calculation, then you need to know that according to the Micrsoft support web page, the system uses:
4 GB for game caching and for other hard drive-specific game elements for games that support the use of the Xbox Hard Drive and 2 GB is reserved for use by the Xbox 360 backwards-compatibility software that allows you to play older Xbox titles on the Xbox 360 console.
Therefore you actually have about 14GB of storage.
NEXT YOU NEED TO KNOW:
Arcade games take 50-200MB (on average). Hi-resoulution action games take much more (Older game disks hold 5GB while newer games can run up to 8 or 9GB). Downloading movies will also gobble up that your GB space fast!
If you are planning to use a 20 GB disk. Keep it strictly for gaming. Go to a larger drive if you do heavy gaming or plan to store movies. Also remember that downloaded demos are usually >1GB each.
Not sure since the smallest drive was a 20Gb. Also, you forgot to mention what types of games. Arcade or Game Saves?
depends on your xboxs' memory space and how much space the game takes up.
Roughly 10 or 11.
the xbox 360 arcade can play the same games as the normal xbox 360
2-4
To download arcade games you need xbox live, but all you need is a silver membership which is free.
Currently there are no Kinect-enabled games on XBOX Live Arcade, but games using it have been announced.
The Arcade console supports all xbox 360 games.
Yes, there is a list of games that you can play on it.
If you have an Xbox 360 Arcade i don't think it can read old xbox games.
Yes it can you.
About two differences: one: the xbox three sixty has a harddrive two: the xbox arcade comes with free arcade games but doesnt have a hard drive
I think you can. I don't own an arcade but I believe that ALL types of Xbox 360's can play xbox games. Look it up on google.
The Xbox 360 Arcade can play the Original Xbox games. Where the newer Xbox 360 can not. On the Arcade you can also download other old games. But sometimes you can do that on the other system.