New Hard Drive over 128 GB on Dell 4600 - but only recognizes 128 GB!

The reason why it is not recognize by the other computer it is because the operating system of your computer is different from dell.

Look at the "connectors" end of the disk-drive.
There will be a set of thin pins for the "data" cable,
and thicker pins for the "power" connector,
and a smaller grid of small pins.
It's these pins that will be labelled/engraved on the casing:
MA(ster), SL(ave), C(able)S(elect).
Move the jumper to the "slave" setting.
Connect to the power connector.
Connect to a "data" cable.
When you add power to your computer, it should recognize the drive.

It sounds like your sound card has gone out - a VERY easy fix...Here is a video that sould take you step for step...

I BELIEVE THAT WD PROVIDES A CD WITH "WD DATA LIFEGUARD UTILITIES." IF YOU USE THAT DISK AND SELECT "DRIVE TO DRIVE COPY" SELECTION. THIS SHOULD CREATE A CLONE OF YOUR ORIGIONAL DISK. SELECT THE NEW DRIVE TO BOOT FROM EITHER IN BIOS SETTINGS OR FROM THE BOOT SELECT "F12" OPTION.
THE PC SHOULD BOOT FROM THE NEW DRIVE IF SELECTED

ED P

Did you check the MS hardware compatability list http://www.microsoft.com/windows/compatibility/windows-7/en-us/default.aspx

From the Dell specifications page for Dimension 4600:
Memory
Architecture
Dual Channel DDR SDRAM
Memory connectors
Four
Memory capacities
128-, 256-, 512-MB or 1-GB
Minimum memory
128-MB DDR SDRAM
NOTE: Between 32 and 64 MB of system memory may be allocated to support graphics, depending on system memory size and other factors.
Maximum memory
4 GB
Memory type
PC2700 (333-MHz) or PC3200 (400-MHz) DDR SDRAM
(non-ECC)

did you configure the 160GB hard drive as second???
there is a shorting pin between the ribbem cable and the power cable.
take a look on the hard drive, there should have adiagram shows where the shorting pin need to go to make it as secondary drive.
install the hard drive as secondary drive.
if you want the drive to be the primary. you nee to install the operating system on it.
with out operating system the machine will boot up in to DOS only, and a error message telling you the drive has no loader.

Sounds like you lost an ide channel, swap the ide cables around, primary to secondary and secondary to primary. and see if it recognizes the hard drives and not the cdrom.

I lost an IDE channel and had to install a sata hard drive or run the hard drive and cdrom on the same ribbon. If you run HD and CDROM on same ribbon set both to CS (cable select)

Put the CD in your CD Drive and shut off the pc. Then start it up again making sure the CD is still in the drive. You will then be asked if you want to boot from CD. Press any key to confirm this (it might skip asking you if it detects that your hard-drive is already blank) Then you want to let it run its install routine. Im not sure what options it will give you but the ones you are looking for is FULL install.

Did you reinstall windows or was this a second hard drive that you installed?