Picture of A guide to controlling things with varying input (via arduino)
the heart of this project is a) hooking up a sensor to arduino analog input and b) programming with the if...else statement.
this particular project demonstrates a computer cooling system to maintain certain temperature within a computer tower.

i used the following items and ill explain each later. some aren't needed or can be substituted.

Arduino uno (the programming is so simple just about any arduino or other microcontroller will work)
a 9 volt clip if you don't want to power the arduino via computer
an Atx power supply
jumpers and alligator clips (alligator clips just for testing)
MintDuino kit (suggested for its built in stuff, totally not needed usually)
a thermosister (mine came with the arduino ultimate kit)
usb cable for arduino
I used the seeed studio relay sheild, other things work too
A fan or peltier device
a box to cool (my desktop computer)
the box motherboard/cpu (as something that gets hot)
LCD display (for pizazz)
a 16 pin header (to solder to LCD)
an ide cable or a floppy cable, etc. to extend lcd
wire for extending things

the Arduino IDE software and drivers

multi-meter for testing
a wire wrap tool or soldering iron
small flat-head screwdriver for relay shield
any other tools you feel are handy for this stuff

pictures of materials and how to use them will come in following steps
WebsWalker2 years ago
If you want a more detailed Instructable about using PC power suply as lab power suply check this video I found on Youtube:
This guy explain everything and shows how he proceeds. I think it is a nice complement to your brief introduction.
However nice tuto, thanks a lot!