so final question about upload/download speed?

Both are important for different reasons. In a game you need to send positional data about what and where your character is and is doing. So you need upload speed for that. You need a greater download speed because in multiplayer games there can be multiples of that information coming back to you (depending on the number of players) In a game lobby there is a statistic called Ping.....the lower this number the better this is how many milliseconds it takes for you to send a ping request and get the ping acknowledgement back. For example I have 25 mbps Down and 15 mbps Up...this is really quick and I usually never see problems. But if you are on 4G internet then the Down could be 15 mbps but the up may only be 1 mbps. so there can be lag problems.

Upload speed does not affect online gaming unless you are hosting the server. As for download speed it does affect your online gaming speed as you are downloading data from the server host.

You did not include the processor for the Macbook. I am gonna have got to go with the Alienware or the 2.4Ghz Macbook. I am gonna go along with the alienware seeing that it has higher specs,the Raid HD. Macbook is the professional one although.