Confusion about the difference in Model Number - Studio XPS

Hey guys,

Forgive this if it sounds like a noob question but i'm having some trouble figuring out the diffence between the different lines of Studio XPS 16's.

I've got a 1640, Intel 2.66Ghz processor 8GB 1066 memory, Ati 3670 512mb video card.

I've got a (I believe) 1645, Intel i7 720QM, 8GB 1333 Mem, Ati 4670 1GB on its way.

But what constitutes a 1647, Originally i assumed that anything with an i5 Dual core or i7 Dual core like the 620 would be a 1647 however i'm noticing some people posting within their specs they have a i7 720QM/820 as their processor in the 1647.

My question is basically what makes the difference between a 1645 and a 1647 aside from the processor.

For me in the list of parts under the dell.ca order status page it simply lists. Dell Studio XPS 16, later on it says

DELL RESOURCE DVD,BACK-UP,XPS 1645
But elsewhere it says
8X DVD+/-RW SLOT DRV, XPS 1640

Now i can assume (probably safely) that this is a 1645 and that the 1640's refer to the reuse of 1640 parts that haven't had their names updated to reflect a different system name. But that doesn't seem to answer the question of whether a 1647 comes with a i7 quad core processor and if there is anything else that is enhanced (depending on your view of quad vs dual) over the 1645.

Hopefully this makes sense and hasn't already been easily answered elsewhere. (I swear i looked )
Thanks,

 

I think you actually have it all figured out pretty much right. The 1645 is the only one available with the i7 720 or i7 820 quad processors. The 1647 is available with the various i5 dual core processors and also with the i7 620 dual core processor. I believe that the 1647 variations also use a different chipset than the 1645 configurations.

Les