SSD may help you a tad, but you still have to justify it economically...i.e. the speed boost will pay itself back in time savings...
Also, nice score on the Mac Pro btw

...but as it seems you scored a one time offer...do you need it now? It doesn't appear that you could've afforded one without this deal you got. So perhaps you don't need the Mac Pro NOW, and were getting along with the MacBook Pro.
Therefore, my advice would be to keep the MacBook Pro, and save for a month or so...
Then you should get the following upgrades...
- RAM: 4GB or 8GB from eBay (or somewhere else you may know)
- HDD: yes HDD's. Get however many in whatever size you want, and consider setting up a RAID 0 for speed
- Graphics : Get an 8800GT or a GTX285...whichever you prefer
Those upgrades for me cost ~AU$700 on top of the AU$3,300 the Mac Pro cost.
Just be patient, and in a month or so you'll have a pimped out Mac Pro AND a sweet MacBook Pro
- Michael
btw, I used to live in Belfast, it's where my family comes from. Rough place, but the people can be golden
