I can't think of any dvb programs that can't use the sg-2100, it is probably the most common diseqc motor, at least on this side of the pond. If you are going to use a motor with a pci dvb card the sg-2100 is the one you want. It will move your 80 cm dish easily.
What you will need to find out is if your Pinnacle 400i card is supported by the dvb software you decide to use, not all software supports the same cards. I noticed in Dvbdream there is a choice for a Pinnacle dvb device, not sure if it is your model. Go to the home pages of MyTheatre, Dvbdream, Altdvb, Progdvb and any others you can think of and check for compatability of those softwares with your Pinnacle card. They usually have a list of what cards they support.
As to your question of Progdvb and how it makes the motor work, you first need to have the card installed and Progdvb needs to recognize it, then you can proceed to settings, diseqc, and select your card, then add positioner, then switch(if using one) then add your lnbf.
You will also need to decide if you want to move the motor with diseqc1.2 or Usals, most software will do both, Usals is much easier, especially if you are just setting up and aligning a new dish.
It would be much easier if you had or could borrow a set top box to align your dish, then just switch over to the pci card once you have everything set, its tough setting up a dish with a pci dvb card setup, not impossible but difficult.
Dvbdream does not have native Usals support but you can use raw diseqc commands and it works fine that way. Mytheatre works nicely with Usals, its not free... $40. Progdvb supports Usals as well, all of them support diseqc1.2