I have a WD2500 installed in an external drive enclosure connected to my comp. running XP. I have the jumper on cable select. It is connected via USB. When I turn the enclosure on, the drive spins up, and the icon in the system tray shows up like it should (for safely removing hardware). When I go into windows explorer, the drive does not show up. I have gone into device manager and updated the driver for this USB device, and it tells me that this device is running properly, but I am unable to access it via windows explorer. Please help.

This enclosure allows for the reuse of older hard drives. Earlier computers connected to the hard drives via a flat cable IDE. These enclosures convert the older style drives to a USB interface. It also takes the hard drive usually installed internally in the computer case on the IDE cable and locate into an enclosure externally allowing for them to be portable.

Check the jumper settings of the IDE hard drive you have in the enclosure for compatibility in your setup. (Choices are Master, Slave and Cable Select).

get external hard drive shell, place the hard drive in it, the connect via firewire or usb all your info should be intact except if its a crash

OK your hard drive is an ATA drive.
You motherboard will have two hard disk controllers, on the 1st controller the ATA cable will have two connectors - a connector will have the C drive hard disk attached to it and the jumper on the hard drive will be set as the Master drive. You may also have a CD or DVD drive connected to this cable, if so then the CD or DVD drive will be jumpered as a Slave drive.
If the second connector does not have a drive connected, then you can connect the second hard drive to this connector BUT it needs to be jumpered as a Slave drive.
You may elect to connect the second hard drive to the second IDE controller instead on the first controller. If there aren't any drives on the second ATA cable then the second hard drive can be jumpered as either a Master or Slave drive.
If there is a drive on the second ATA cable you need to determine the jumper setting of that drive and then set the jumper on the second hard drive to a different setting. BOTH drives on the same cable CANNOT have the same drive setting.
After installing the second hard drive, check the BIOS configuration of the second hard drive, if the hard drive is detected then when Windows boots up you will see the hard drive and its contents.

It is in my experience with hard drives used in external USB enclosures - the jumpers are not nessessery.

external USB hard drives do not need to be jumpered, if your computer does not recognize the ext. drive probably it is because the enclosure is defective, when you connect the USB cable you should get the "ding-dong" connection sound.

If you think that your computer recognizes the hard drive then jumper it as "secondary" or "cable select" and install it INTERNALLY, then transfer your data, that will prove that there's a problem with the ext. enclosure.

One more thing, maybe the USB port you use is malfunctioning, try one that you know that works (assuming that you have other USB devices that work).

You do not need to install a driver for Windows XP and Vista, it is already built in. The CD may however contain optional software for initializing the hard drive the first time, and for making backups later.

Do you know if the hard disk is good? Does it spin up when you turn it on? You can hear and feel it spin up.

If this is not a SATA drive, make sure that the jumper is set correctly. Most enclosures require the drive to be jumpered for Master, sometimes for Single or CS. Check the top of the hard disk for a guide to how to set or remove the jumper.

You might try connecting it to different USB ports, some are faulty.

You can slave the EIDE hard drive off of the CD Drive, as long has it is also EIDE. There should be a flat grey ribbon cable plugged into the back of your CD Drive. That IDE ribbon cable should have 2 connectors on it, one of them should be plugged into the CD Drive.

If it does not have 2 connectors, then go buy a new IDE ribbon cable that has 2 connectors, they are cheap. Or ask a friend, he/she might have extra, I always do.

Make sure you have the jumper settings correct on both drives. One will be the master, the other should be the slave. Or set both to "select select" and let the computer decide. The jumper is a little black jumper that connects 2 pins together on back of the drive. This tells the drive if it is a master, slave or cable select.

There should be a sticker diagram on each drive denoting the correct pin-jumper setting.

One other thing, when you hook up 2 drives to 1 IDE cable, both drives share the bandwidth. If you are using one of the drives, don't try to use the other, major performance slow-down.

Also, you don't need to slave the drive. You can get a Hard drive enclosure and make the drive an external drive connected by USB. They are also cheap, but make sure the hard drive has a partition and is formatted before installing it in the enclosure.

http://www.geeks.com/details.asp?invtid=COSMOS-525U2-SIL&cat=HDD

 If your running XP , go to control panal , Admin tools>Computer Management >Storage > Disk Management . Look for it there . If its there see if it says what file system . If none format it . If it isnt there then chack the jumper on the hard drive it self . It should be set to master or cable select . 

Try a different USB cable. Try a different computer. If those don't solve it, it a defective enclosure. I seem to have a handful of defective ones myself. ZT3000 "Beta tester of "0"s and "1's"