Abstract
In the abstract, you'll generally be limited by your inter-switch links. You probably won't see maximum performance out of consumer grade hardware either. For example, the PCs probably can't sustain gigabit speeds reading and writing to their hard drives.
Time for maths
You'll need to find and compute several things to answer you questions. You'll have to consult with manufacturer specifications, and do some basic math.
Single Switch
If you only had one switch, you would only need to know the backplane speed of that switch. That will be your limiting factor of your network. If you have a nonblocking switch (see below), your nodes will be able to communicate at full speed.
Multiple Switches
If you have multiple switches, you'll need to find the backplane speed of all the switches. You want the backplane speed to be the number of ports times the speed times 2 (for full duplex) (For example, 8 ports x 1Gbps x 2 = 16Gpbs). Alternatively, you could look in its specs for the phrase "nonblocking" (wikipedia, DSL Reports, Cisco). Then, you'll need to create a network map of what nodes are communicating with what other nodes. You'll need to factor in the communications of all the devices of your network, and how they cross uplinks between the switches. If you exceed the rate of your uplink, that is a limiting factor, and your network becomes blocking. Professional switches usually have the next higher speed for their uplinks. For example, a 100mbit switch would have a gigabit uplink, and a gigabit switch would have a 10gigabit uplink.
An example of professionals referring to this with specific model numbers. Another example on Cisco's forum. Additional reading