Mac Pro vs my old Windows computer

[Sheiky]

or, he could buy an external hard drive and just hook it up to the firewire.

That's a good point. Firewire, USB3 or Thunderbolt would give good results.

So you are losing speed any time you put the files off of the main drive to a second drive, whether a hdd drive would make up the lost speed or not i do not know.

Having your operating system, programs and photos all on the same hard drive would probably be even slower than using an external drive with your photos in combination with a fast primary SSD. You don't have to put all the files from camera to SSD to external hard drive. If you keep the Operatng system, programs and RAW-cache on the SSD and the files on the external drive you're probably good. Obviously if you're using the laptop daily for your photographs, this process might bug you in the long run.

The Macbook will have much better performance than the Dell, if your Dell is like mine always bogged down with adware, malware and viruses.

i am using the dell to type this, and from my personal exerience of these two i would choose the mac book pro over the dell.

Can I ask you this: what type of person are you? Are you the type that buys equipment and uses it as it is delivered. Or are you a person that likes to tweak the equipment for better performance? As I said before, annoying Dell apps and viruses tell more about a user than about a system. If you know how to "clean up" a factory laptop like Dell you chances are small that you experience the problems you're talking about. But if you don't or simply don't want to, you just have to face them(the Apps). The point of these factory system builds like Dell or HP is that they need to make commercial for their own good and invent all different types of Apps that keep you using the Apps with their name.
I don't mind to clean up my system and tweak it where I can(I build my own system so I don't have these annoying Apps anyway). Better yet I kind of like it to be in control for once If you don't want to bother and all the rumors about Macs(no viruses, no speed loss over time, no maintenance) are true, then you're in the right spot with a Mac.