So, i have a HDD i had installed Mandrake on, just to test it out. Then i waited till i got a new comp and now i put in the HDD but get a Error loading OS message. Could this be out dated BIOS, or something to do with Mandrake....do i need to repair it or something like that.

If the hard drive is not located in the same position as when it was installed then you will have problems because the partition IDs have changed. You might try sticking it in the same position and seeing what happens.

Else you will need to boot the 1st CD to rescue mode and mount the root partition. You will need to edit the bootloader conf file and fstab file. Are you using lilo or grub? I haven't used Mandrake in awhile so I do not remember what happens when rescue mode boots. Do you remember which partition is your root, swap and so on?