lol, wrong rack.
to clarify, im just confused on how it all works.
having a rackmounted mixer, effects, and whatnot...
Long story short:

A rack setup is no different than anything else, it's just all contained within a case offering a universal mounting system so it's easy to mix and match vastly different things. Rack setups are usually controlled with a universal interface, such as Midi, as opposed to having to reconfigure everything individually every time you need to change something.
ESP LTD EC-256 and a Fender Deluxe VM
A rack is simply a stack of things like compressors, limiters, tuners, power conditioners,Multi Band EQ's, etc. Slash has a "rack mount" Wah pedal, which means it is not in his pedal board. (ok, so the actual pedal IS down there, but where the effect happens happens in a rack.) but included in a stack of other effects in a cabinet type console.

EX: http://www.stefanleibing.com/equipment/icons/LiveRack.jpg
In short, it's a protective case for your gear. Most high-end effects are 'rack-units' designed to be held in these cases.

Racks have 3 major advantages over a traditional rig as I see it.

1. Everything in one package
With your pre-amp, power amp, effects, power supply, compressor, tuner, etc. all in one proctective case, it's makes your life alot easier.

2. Modular Systems!
You can buy seperate pre-amps and power amps (among other things) so you can get a much more unique tone. For example, you could take a Marshall JMP-1 pre-amp, and hook it up to a Mesa 2:90 Power amp. You CANNOT get this in combos or heads.

With a good MIDI controller, you can have acces to everything with just a click of a button. Picture this, You're in the middle of a space-rock type of part of a song with your band. Your using your clean sound, with a little delay and chorus. In about 5 seconds you need to switch to a hot overdriven lead sound with heavy reverb. Instead of turning off delay and chorus, switching to overdrive channel, then stomping on your reverb pedal, you do it all with ONE STOMP.
Dissonance is Bliss

Signal Chain:
Carvin CT-4
Ibanez TS-9
Carvin Quad-X
TC Electronics G-Major
Mesa/Boogie 2:90
Ear Candy BuzzBomb

Member #4 of the Carvin Club
I suppose I should also note that most rack rigs are preset based and you'll probably spend a lot of time programming in each individual preset. This is one of the distinct disadvantages to a rack rig, but it can pay off in spades if you're playing out a lot and don't want to have to dial in everything every night. I should also note that in preset based systems, you generally lose a lot of the "on the fly" adjustment capability that a more traditional rigs can offer.
ESP LTD EC-256 and a Fender Deluxe VM
Yea, there are a lot of pro's, and a lot of cons.
I'd love to invest in rack gear, having that sort of flexibility on stage would be great.
But i'd rather be able to fine tune things via pedals, and on the amp while i'm sound checking or playing or whatever.
May invest in a tuner, and maybe look into power amps and pre amps in the future, not ready to start investing THAT much money though.