Everybody is giving you v good advice regarding setting your old drive as a SLAVE...however...some of the advice is overlooking something!
Your new mother board may only have 1 x IDE port...and your new ATA hardrive (if it is an ATA drive) will of course be plugged into that....and then you will almost certainly have a CD drive or DVD writer etc...which will also come off that same cable and IDE port. The CD or DVD drive will be set to slave...and the new Hard drive will be set to master.
This all being the case .....you are stuck ...because you can only run 2 x IDE devices off 1 x IDE port.
Its not a problem though!! you can purcahse a seperate card for £10-20 which is a contoller card with another 1 or 2 ide ports. The car would fit in one of the WHITE PCI slots. This will give you another 1 or 2 IDE PORTS to play with.
On the other hand you may just find your new PC motherboard does have 2 x IDE ports....in which case its easy.
So my advice is....check to see if your new PC's configuration is ATA ...and also how many IDE ports you have on the motherboard (Dell will you tell you all this...or check the docs that came with the PC...or just look inside the PC)
If your new drive however is a SATA (serial ATA) drive....that will be connected to the Serial ATA port.....and if that is the case.....your CD/DVD drive...will most likley be connected to your IDE port.
Now if thats the case....then the DVD will be set to master....is which case you set your DRIVE to slave...and slot it in on the end of that cable.....or if it were me..prob set your drive to master...and the DVD to slave.
SLAVE OR MASTER: This is simply done by looking at the various configurations normally on a label on your drive. You simply set the jumper block accordingly....or in a lot of cases....you can remove the jumper altogther ...and that will set the drive to slave. If the config label is not there....check the drive out on the drive makers support site...and they will tell you which way to set the jumper block. ITS DEAD SIMPLE THOUGH...and you won't hurt it by getting it wrong....it just won't be recognised if its wrong!!
Make sure you connect the old drive properly.....the IDE Cable will have 1 wire on 1 side which will be red.....and that almost always goes next to the POWER cable which will be shaped to fit one way...and will also have a red cable...make sure those cables are NEXT to each other (red next to red) .....push the IDE cable in v carefully or you will bend the little pins!!
EASIEST OF ALL!
Finally...if you want it really easy...and in a way more use!! You can purchase for about £5 off ebay, a USB to IDE converter cable!
This will come with a 240v Power cable and everything you need. You simply connect it up (all done externally and without ripping the new pc apart) setting your drive to master.....and then under My PC...you will see your connected old drive appear. You can drag and drop to your hearts content....and best of all ...using the same drive connect it to any other PC with a USB port....and do the same. Its all drag and drop....when you're done....you can store the drive very carefully wherver you want.
I have got a seperate drive I use for this purpose...and I store it away from my office...so if GOD FORBID...there was a fire at the office.....I still have my vital files (templates and docs etc) all backed up on the drive!!
Hope that all helps you squire!!!!