I can't find this information anywhere. I currently have a SATA drive, but it'd be great if I add an additional SSD. Is this possible?
If you go to the dell website and put the service tag number in. You can get the original configuration and specs.
The service manual and owners manual can be find here the service manual only shows one hard drive.
I am assuming, as dangerous as that is, that you are asking about internal drives. The most likely answer is no, if it didn't come with two HD then you cannot add an internal one. I know some of the gaming laptops came with two HD installed as configured with RAID 0
If you have a PCMCIA slot I think it's called cardbus now you may be able to find a HD that will fit entirely in that slot.
After reading Jeff's blog post on the M1330 I assume there isn't room for an additional drive, else I think he would have stuffed one in it.