I got a new WD6400AAKS OEM hard drive today and had a question about installing this in my Dell XPS 400 as a second hdd. Since I've never installed a SATA hdd before (only IDE on my old computer) I was a little confused (the WD6400aaks came with no jumpers)
I plugged in my new hdd into the sata port in my motherboard, plugged in the power cable, turned on all the sata connectors in the bios to ON and my hdd is not showing up. When I was turning on all the SATA selection to ON in the bios, when I got to SATA number 3, the screen went black so I rebooted the computer and it said "no disk found, press f1 to continue" and after I pressed f1, the computer booted into windows XP home fine but my new hdd doesn't show up anywhere.

Are there drivers I need or something I'm missing here. Any help would be appreciated.

Try going to Control Panel > Administrative Tools > Computer Management > Storage > Disk Management. You should be able to see it there if there is no problems, and then format it from there.

you might also want to go into bios and change the boot order it it has changed

As suggested by Pyro, get into Disk Management, but once there, try clicking on "action" and hitting "Rescan Disks" from the drop down menu. Once it shows up in the bottom on the right of the window you should be able to right click it, and hit "format"
I'm working from memory here, which sometimes isn't all that great, but it seems to me, that's how I cured my last HDD install which wasn't recognized right off the bat.

If those don't solve your problem, perhaps this will help. I think I had a similar problem.

http://www.tomshardware.com/forum/ [...] on-problem

Doing the operations within Windows Disk Management is the best way, as several have said. However, they've skipped a step. With a brand new disk, the first thing you need to do there is to Partition it - that is, define how you want its space allocated to drives. You can choose to use it as one volume that uses the entire space available, or you can create two or more separate partitions that will each behave as individual drives. This assumes your OS already supports "48-bit LBA". That support was missing in the original release of Win XP, but was added with Service Pack 1 and all later SP's. Without it, the maximum volume size you can make is 127 GB; with it, you could make a HDD volume up in the petabyte region if anyone ever makes one! So, if you are not allowed to make a Partition over 127 GB, you will need to update you OS BEFORE proceeding.

Once you have created the partition(s) on your new HDD, you can then Format each one (if more than one) separately. Only after you have done both of these operations will Windows see the new drive(s).