I think i'll just give up on trying to recover my data. it was just some emails.
I tried the XPS 420, but it said that the drive is not bootable any more.
This is my new problem:
http://forums.overclockers.co.uk/showthread.php?p=18177523#post18177523
As long as you've not tried to install anything over or format either of the drives, it should still be bootable.
Did you remember to turn the SATA controller back into RAID mode on the XPS 420? Did you have both drives connected to the same SATA ports as before? Try switching them around since you might have gotten them the wrong way.
What is the RAID controllers BIOS saying?