Nice guide! I think it would be worth putting in an extra section about 3D work. As has already been mentioned, you do need a good graphics card. However:
- you need a good balance of processor, RAM, graphics card.
- as far as graphics cards go for 3D, its best to look for nVidia CUDA processors (especially those manafactured by PNY), or ATI Firepro.
Also for a note on graphics cards in general, its not just the card you buy but the manafacturer. For example, and nVidia GTxyz made by PNY is (or should be) much better than one made by the cheaper but lower quality brand XFX.
I can't find the link now but there are a couple of lists of graphics card rankings (one is going slightly out of date) that it is worth checking to make sure you get the best graphics card for your budget.
Perhaps power supplies should have a mention as if you are wanting to upgrade your computer (especially graphics card wise), you need a good PSU.
Thanks
~Sheppy96