Processor:
Intel Celeron 300

RAM:
1 128MB stick of Kingston PC100 RAM

Mainboard:
Abit BH6 Mainboard

Case:
Enlight MidTower

Sound Card:
Aureal SQ2500 Sound Card

Video Card:
Elsa Erazor III w/32MB (AGP Card)

Phone Modem:
Creative 56k Modem

Hard Drive:
Western Digital 20GIG HD (IDE Device)

CD/DVD-ROM Drive:
10x Pioneer DVD-ROM (IDE Device)

3.5" Drive(s):
3.5" Floppy Drive

First and foremost make sure you have some good tools. You don't want to be running around the house looking for something mid-way, so its best to have all the tools within your reach. All you really need is a Phillips head screwdriver, and a pair of needle nose pliers (just incase something falls in the case). That's really all I ever use.

Before you start you'll also want to make sure you have all potentially electro-statically charged items neutralized (this includes you), static electricity has the potential to ruin your components. To neutralize any static electricity which you may be carrying, simply plant your feet firmly on the ground and touch either the case or power supply, don't do this while the case is plugged in or you may just get a jolt. For the truly paranoid, you can also pick up a static wristband for about $10 at your local CompUSA and just be wary of any static that may be lurking nearby.