If your hard drive is close to capacity, it's time to add a new one.
First, determine whether your current drive uses an IDE/AT interface or an SCSI connection. When you start your computer, you might see a reference to an SCSI device. Otherwise, your current drive probably uses an IDE or AT interface. AT drives are faster than the older IDE drives, but they work with IDE drives.
Before you start, back up data, then power down and unplug the computer.
Then, with the case off, check your computer's chassis to see whether you need a mounting kit. You should also look at the flat, gray data cable that connects your current drive to the hard drive controller, which is found either on the motherboard or as a separate board in a motherboard slot.
If the cable has three connectors, you're ready to install the new drive. If the cable has only two connectors, you need a new one, available at most computer stores for a few bucks. One end of the three-connector cable plugs into the hard drive controller, and the other end hooks into the drive itself. The third connector--located closer to the end connected to the drive--is for the second drive.
You'll also find three connectors on the back of the new drive. The widest takes the 40-pin cable connecting the drive to the controller. The power connection has a white plug--usually with a yellow and a red wire and two black wires. If you don't find a power lead from the power supply that isn't being used, you can use a splitter, available at most computer stores for a few dollars. Finally, there are four sets of two "jumper pins" and a small "jumper" that connects one of the four pairs of pins together.
The jumper pins set "master" and "slave" designations for both drives. Jumper pin information is usually printed on the drive, and it's also available at the Web site for that drive maker. If the new drive is a slave, the installation is easier because your old drive remains the one that boots the system.
Connect the data and power cables to the new drive, and start the computer. Follow the instructions on your screen to enter the CMOS, or BIOS setup program. If you have a Compaq computer, you'll need to consult the manual about the CMOS setup. Use the "auto detect hard drive" option so the computer recognizes the new drive and sets up appropriate settings.
Assuming the new drive is the slave, once Windows is loaded, click on Start and then Run. Type the word "command" in the Open: box and then click OK.
You are now in DOS mode. At the DOS prompt, type "fdisk" and press Enter. Select the second drive, and create partitions. I suggest you use one large partition. Your computer will restart itself. Go back to the DOS prompt and type "format d:" (where d: represents the letter of your new drive). Press Enter. Note that Fdisk.exe and Format.com are programs found in the Windows/Command folder. Be careful here because the Format command will wipe out anything on that drive.
If your new drive is to be the master, you need a Windows startup disk and the Windows CD-ROM. You can create the start-up disk before you start by double-clicking on My Computer and then on Control Panel. Open Add/Remove Programs and select Startup Disk. Follow the instructions to create the disk.
When you have installed the new master drive, just boot from the floppy disk. It will ask for your input in setting up partitions on the drive. When you have finished, restart the computer and select the option that lets you use your CD-ROM drive. Insert the Windows CD-ROM, then type "e:setup" (where e: represents the letter of your CD-ROM). Windows will format the new drive and install itself.
You should now be able to start your computer and load Windows. Remember to remove the floppy disk. You still have to reinstall all of your programs, but there is an easy way to do most of that with a $65 program called Ghost by Symantec at http://www.symantec.com.
If all this seems overwhelming, take a look at http://www.iupgradeinc.com. The $79.95 IUpgrade product consists of a special hard drive cable and a controller that plugs into a slot on your motherboard, which makes installation a snap. It's well worth the money.
Jeff Levy hosts the "On Computers" radio talk show from 9 a.m. to noon Sundays on KFI-AM (640).