as far as I know all those rendering programs are CPU intensive... maybe you'd be better going with more cores and RAM. If you don't need the GTX470, I'd say go with a 5770 or 5850... they'll keep you good for DX11 going forward... in terms of cheap CPU/RAM alternatives, I'd suggest looking at the 1055T (6 cores for ~$350ish) or possibly the SR-2 with 2x quad Xeons for a total of 8 cores, but you could cram 48GBs of RAM there... just suggestions...
3DSMax specifically has a plug-in called vray or metalray(Can't remember which one) thats GPU bound and is exponentially faster than CPU rendering.
Also, keep the GTX 470 as nVidia's software is just better in this regard.
You should join the "3DS Max club" here on OCN. Just visit the "Other Software" section in the software sub-forum and you'll run into that group. There are plenty of guys in that group that has experience with this stuff already.