And now for the simple answer:
Make a startup disk. Go to Add/Remove Programs in the Control Panel.
Insert a blank, formatted floppy disk.
Go to the last tab - "Startup Disk" and click "create disk."
When that's finished, you have a floppy that will start your computer in DOS.
You will need:
A Windows 98 install disk
Your license number, which can be obtained using a keyfinder
if you don't know what it is
Drivers for your hardware and whatever software you wish to install, including license keys.
Put your Windows disk in the CD-Rom. Put your floppy in the A: drive.
Shut off your computer. Restart, and the computer should start with the floppy.
You will get a DOS prompt, which looks like A:\>
Type format c:
You will be instructed that all files will be deleted. Press Y.
When the format is complete, you will be returned to the prompt.
Type setup and the letter of your CD-Rom - such as
The Windows install will start. Follow instructions and insert your key when ready.
Windows will probably find most of your drivers. When the installation is finished, open your system properties by pressing both the Windows key and the Pause/Break key. Check your Device Manager for any yellow exclamation points or question marks on any of the devices. It is possible that you will have to download a driver for any of the ones that aren't working properly.
Install printers, scanners, and so on.
At this point, before you go on the internet, you need to have an antivirus and firewall installed. If you have programs you've been using install them. If you have a burner on your newer computer, you can download the install file for an antivirus like AVG and a firewall like Zone Alarm.
Then get all the Windows Critical Updates. Install all your other programs. Add spyware programs like Spybot Search and Destroy and Ad-Aware.
The less you load the machine with, the faster it will run.
Have fun and good luck.