The biggest issue is with power draw.
The equipment could very likely draw more power than an individual circuit could handle, especially if you have a powerful PC and/or amp(s).
Getting ready to get started with my install (once the equipment comes in) and have noticed that many posts speak of wiring equipment to the battery, with an in-line fuse within 1 foot of the battery. What would be the impact of adding a circuit for each device (PC, Amp, Sirius and monitor) to the fuse box and utilized those fuses to provide protection for my equipment?
Admittedly a newbie question - but I'm a newbie...
the first thing you should realize is that the fuse at the power source (which in this case is the battery) is to protect the wire from catching fire if short-circuited or overloaded. while it does provide protection for devices connected after it, that's not it's primary purpose.
you should avoid powering devices from the car's factory wiring as it is not designed to power additional devices. the best and safest option is to run a thick power wire (fused) from the battery) to an aftermarket fuse block. this method only requires running 1 wire through the firewall, but still keeps your wiring isolated from the car's factory wiring.
using a fuse block allows you to have several individually fused power outputs without the need to run separate wires all the way to the battery. auto stores like AutoZone and PepBoys sell some basic fuse blocks, you can get some better models online. there are several sites (like this one) that carry a decent selection a fuse blocks.
I use this model in my car: