What is the fastest machine known to man?

This has, basically, nothing to do with the computer speed. It has everything to do with your Internet connection, both speed and latency. Invest your money in a lower latency, higher speed connection.

 

Wire your house for single mode fiber and get yourself an OC-255 connection. That'll be about as close as you can get to "instant."

 

And if gaming is your primary use, build a computer. It's not that difficult and will certainly save you money. Don't get a Mac for a gaming rig.

Oh and this is probably the "fastest computer known to man"

http://www.ncsa.illinois.edu/BlueWaters/

 

As said, the speed of your internet connection is going to have a lot more to do with what you're describing (other than game framerate) than the computer.

If you just want it for gaming, you really would get more bang for your buck from a Windows box. If you don't have a friend willing to help you with a DIY, Alienware or another name-brand gaming rig is probably good enough.

If, however, you do want to go with a Mac, it's pretty easy: Go to the Apple online store, start with the single processor (4-core) Mac Pro, custom configure it with a six-core processor for good measure (getting 8 or 12 cores is completely pointless for what you want to do), and a Radeon HD 5870. That'll cost you about $4000.

Then go to OWC (macsales.com) and order yourself a Mercury Extreme Pro SSD drive 120GB (or 240GB if you're feeling particularly rich) and 3x4GB RAM (Apple drastically overcharges for RAM on their BTO systems). That'll run about another $600.

Once everything shows up, replace the 3 factory sticks of RAM with the OWC RAM, add the SSD and install the OS on it as a boot drive, and you're good to go. Keep in mind that while this is a very fast computer, it's built using mostly server-grade components (plus the standard Apple markup), so it's going to be considerably more pricey than a similarly equipped BTO Windows box, even when you factor in a couple hundred bucks for Wiin7Ultimate.

If nearly $5K sounds too steep, either go with a BTO PC, or a 27" quad-core i7 iMac. For about $2200 the iMac is a very nice system that will handle gaming respectably and comes with what is essentially an $1100 monitor (if you buy the same panel from Dell at list price) attached. Add an extra couple of GB of RAM to it, and an SSD from either Apple or OWC (you'll have to pay someone to install it if you buy 3rd party--iMacs are NOT easy to get around inside) for an extra speed boost.

I did the latter, but I'm not a gamer--I wanted the screen, and it happened to come with a decent computer attached to it for not that much more.