Designing my new system

[meat_helmet]

That's a nice build if you do go with it. I would change the GPU and the HDD to this:
Newegg.com |Seagate 500gig sata HDD. I own 5 of them and there warranty is longer then WD
Newegg.com | Zotac 9800GTX+ the reviews are better, also I own them both, there great!

Newegg doesnt deliver to OZ. Still, i can suggest some places. Try looking for the parts you want on staticICE :: Australia's comprehensive computer hardware and gadget price comparison search engine - it will give you some good deals. Other than that these places are quite good:

MSY Technology Pty. Ltd.-The Name you can trust-more than 10 years in computer industry - very cheap, crap service - in Sydney
Mwave Australia: Buy & Save in more than one way at Mwave! - quite cheap, very good service
IJK Online Store IT / Computers - fairly cheap, not great service but lots of gear - Sydney
Australia Online VIP - can be extremely cheap (but its a guy who runs his business out of his house, lol!) - Sydney

I have used all of them, and overall mwave might be the best for online ordering.

From Umart, i suggest these parts for you:

IJK Online Store IT / Computers - Q9550
IJK Online Store IT / Computers - 4GB OCZ Reapers
IJK Online Store IT / Computers - Asus P5Q (before anyone says it, they dont have the Biostar I45)
IJK Online Store IT / Computers - Corsair tx650 (you wont need more than this)
IJK Online Store IT / Computers - Leadtek Quadro FX 570 - A good workstation card
IJK Online Store IT / Computers - WD 6400AAKS

TOTAL = $1498 AU

You may want another 4GB of ram, which bumps it to $1686, and another HDD which bumps it to $1793. So with a case and a DVD drive you will be at ~$2000. If you want to spend any extra you can get a really good workstation card, or spend it getting a bigger screen or somthing. Of course all these prices can probably be cut a little if you shop around and dont mind buying from a few places. Unfortunately we dont have anything that can match newegg for prices in OZ.