you mention a CPU upgrade, can you shed some light on this? That chip is the same chip it came with but a higher clock yea? Where does one buy that?
Upgrade chips can be purchased from various dealers all over the internet - or second hand via eBay (pulled from servers - normally no problem in there). On the 3,1 you can upgrade to 3.0 GHz (E5472) or 3.2 GHz (X5482). The increase in performance is probably not as high as upgrading a MP 1,1 from 4 to 8 cores, so it's up to you to decide whether it'd be worth it.
The upgrade is pretty easy to do - search this forum for the respective threads with info about required tools etc. There's even a video-Step-by-Step-HowTo. You can use guides for MP 1,1 (2006) as well, as those generations are pretty similar in terms of mechanical construction.
On the 2009 MP it's much more difficult, as Apple used proprietary CPU's without attached heatspreaders, not available usually for end users. You can also easily damage those when upgrading. You can on the other hand upgrade the 2009's firmware to that of the 2010 model and get a new daughterboard, allowing to use standard (and better) CPU's again for upgrading (more expensive though).
Also, can someone recommend a graphics card to get? I want movie and photo work to be FAST. Does the graphics card effect the speed for that? [...] I figure it's current GPU is old and crummy.
So i figure there are two brands.
nVidia and ATI.
can someone give me the run down on current low, mid and high end cards for each brand. Flashing or not?
does Os X utilise two cards for processing purposes?
Fastest AMD/ATI card is the 5870 currently. 6870 about 10% slower, but consuming less power. ATI is better supported due to being the official choice by Apple. nVidia may offer better performance for mathematical calculations. For details check out sites like netkas or insanelymac, dealing with Mac grapic cards exclusively.
EDIT:
hmm, i'm still thinking about this.
Would an '09 mac pro be better in the long run?
With it's hyper threading it'd get 16 threads. Is the performance better?
it also uses ddr3.
hmmm. I'm really not sure.
Any advice? was the 2009 a really big step up over the '08?
I thought you sealed the deal already?
Biggest advantage is the change in architecture (Core -> Nehalem/Westmere), which is more powerful clock-by-clock. With it comes the use of standard DDR Ram (instead of FB-DIMM's on the older machines), which is both faster and significantly cheaper.
Serious audio work is a resource hog nearly as bad as video work and will massively profit from more CPU power (cores) - this is probably also true for hyperthreaded ("virtual") cores, which the 2009 has, but the 2008 not.
Biggest problem with the 3,1 could be the Ram. 10GB may be a little tight for huge audio projects and mathematical calculations - and FB-DIMM is expensive. On the other hand you could do it on the antique Core notebook until now, so it might be plenty.
Regarding CPU upgrades i wrote something above. The power of the 3,1 should be sufficient to you (especially regarding your current platform), though the possible long-term upgrade path to the 2010 model with up to 12 cores (24 hyperthreaded) might be tempting (even if being very expensive at this point in time). However, it would probably be less hassle to go directly for a 2010 model if you need/want the power.
In the end no one can take your decisions. The two displays sound like a good add-on, but keep in mind that those are backlit by CCFL's which wear visibly over time, depending on the running hours (maybe those are even the old acrylic CinemaHD displays, which look good housing-wise, but are inferior in terms of e.g. picture brightness to any cheap modern display right out of the box). You can replace worn CCFL lamps, but that costs both time and money and can be a little tricky (i know of tutorials for the acrylic versions - no idea whether the aluminum displays have similar guides available somewhere on the net).
I also have no feeling about how good the price is for Australia.
EDIT:
Would there be any benefit to longevity by getting a 2009 mac pro?
I really want to make the right choice on this as i can only really afford computers every 5 years or so.
Hard to tell. For many even a 2006 MP is still sufficient for years to come. It probably boils down to Hyperthreading and Ram supply/prices being a Plus for the 2009, but not necessarily impairing longevity of a 2008!