Anthony,
In these circumstances, consider a lower specification z420, e.g.,:
HP Z420 Workstation Intel Xeon Quad Core 3.6GHz, No RAM, No HDD, 600W, Win 7 COA > $279 or Offer
That arrives with an E5-1620 which can be sold for about $60, so the net price is about $220. If the seller accepts $250, then it = $190.
To that system, add:
1. Xeon E5-2670 or E5-2680- about $70-$110
2. Add 32GB DDR3-1600 unbuffered - about $140
3. Reuse the Samsung 840 512GB SSD
4. 1TB WD Blue- $50
5. GTX 580 3GB - about $80
That will still cost $530-$580.
Another one, from a slightly different angle:
HP Z420 Workstation Desktop Computer Xeon E5-2670 OctaCore 2.6GHz 16GB 2TB W7P> $550 or offer
That one has Quadro FX1800, which, as it happens is quite good in 2D, but would of course, quickly need something stronger.
Looking at a number of scenarios, the $480 budget would probably only purchase a system one generation newer than
the xw6600 - more in the vein of your earlier listings It's possible with patience though to do a bit better, a z600 with a Xeon X5670 for example:
HP Z600 Workstation 2.93GHz Xeon X5670 6 Core 2.93GHz/ 24GB/ 2TB/ WI-FI WIN 10 > sold for $270
That would leave a good amount for a GPU, perhap GTX 770.
Overall, if the budget could be $600, an E5 8-core system- with SATAIII and USB 3 and etc, would represent a better, and longer-term investment.
This little study did make the z620 (E5-2620) look better and it might work to buy it and replace the CPU with an E5-2670 for $70-90 when possible.
Cheers,
BambiBoom