I think for Sketchup and CAD a FirePro should be working good - theoretically, since Sketchup is still using openGL and there the workstation cards should perform good.
But for Adobe stuff an nvidia card maybe would perform better. But i would take one with at least 2GB RAM. And the V3900 is based on the same chip like the Radeon HD 6570/6670 which is more a lower midrange card and already 2.5 years old...
If you're not using any render engine then i would choose a higher clocked quadcore i7 or Xeon. I would go for the new Haswell based CPUs (i7 4xxx/ Xeon E3 V3) if you can wait a few weeks/months (release should be June/July) or take an Ivy Bridge i7 or Xeon now, but with a clockspeed around 3.5GHz (3.9 GHz Turbo).
maybe one of these:
http://ark.intel.com/products/65727
http://ark.intel.com/products/65725
http://ark.intel.com/products/65523
http://ark.intel.com/products/65719
http://ark.intel.com/products/65520
http://ark.intel.com/products/65702
http://en.wikipedia.org/wiki/Ivy_Bridge_(microarchitecture
And better take 2x8GB RAM so that you can add another 2 Sticks to upgrade to 32GB later (or buy 32GB now if you need it - but maybe not from HP... RAM upgrades are normally highly overpriced at Apple/DELL/HP)
HP Z220 SFF 240W must be a typo... or it is just enough for this system with this low power CPU and GPU. Normally you should buy at least 400-500W to have a bit of headroom for a bigger video card. And the efficiency is normally the best at ~60% load.
And you should definitely buy a SSD for windows/programs...