Just added new hard drive, took out one old one, left in one, and now get nothing.  Can't even BOOT up at this time. Not sure if jumpers and wires are correct. PLEASSSE HELP.  Ok.  It's now Tuesday the 26th., and I'm back to give further info. Thanks to all that have responded even with my scant info.  I apologise that I was running out of time at the library computer and couldn't give more info.  I had a 20 GIG and a 40 gig h.d. in operation, with 2-  40 pin- 80 wire connectors, not the flat ribbon type. The one labeled master was connected to my cd/dvd unit, and to #2 slot on MOTHERBOARD.  The other cable with master/slave was connected to hard DRIVES and to slot #1 on board.  The system did work.  OS on 40 gig drive.  I took out the 20 gig drive, purchased a 160 gig drive, and am wanting to use it as main OS drive. When I re-installed everything, I could not even get any kind of boot up even with boot disk for hard drive.  I will have to ghost OS from 40 gig to 160 gig once system starts functioning again.  Therein lies the problem. I must have wires and jumpers wrong.  Any Ideas out there??  Would appreciate any help and I thank you in advance for it.  Gotta start doing my music but can't obviously.  Thanks again!!!!!Did you install the operating system?hopefully you don't have the same problem i did, and shocked your boardIf the OS is later than WinME you cannot simply swap a drive in there from another machine and expect it to work...
More details on what you are trying to accomplish here.wait did the op put the new hard drive in plus the old one?