Upgrading Mac Pro question

hi there,
I am debating whether I should upgrade my Mac Pro. Right now I have the following

2x2.66 Ghz Dual-Core Intel Xeon with 7 gig of ram

Obviously there are two cpus here. What I want to know is it wise to get the new IMAC or is that just one CPU. One downside of if it just 1 firewire port

Or

If I want to spend a bit more and upgrade to Mac Pro, which is best

I do lot of HD video editing and graphic designing.

What your currently have is probably good enough so I would think spending money on something else might be a better investment for you. I can see you are editing HDV, which can easily be edited on systems way less powerful than yours. Maybe you might be interested in spending your money on education, new production equipment, etc.

Just personal opinion, but its not always important to have the latest and greatest computer. Stick with what you have for as long as it is working for you, then upgrade when its not.

The high end iMac is quad-core so it will be like your Mac Pro in that aspect. Do you want an all in one or do you want the tower with more upgradable options?

honestly i have no desire to spend money but being in the business every year i upgrade my equipment so I can get my money worth that particular equipment. If I was to sell Mac Pro next year, would it's value diminish?

What do you this it's worth right now

2x2.66 Ghz Dual-Core Intel Xeon with 7 gig of ram with 250 gig of hard drive?

vs

same thing and if i upgraded to another 1 tb drive and additional 9 gig of ram

Trust me i am not interested as I love this machine but just trying to do the math