As your receiver has an embedded CAM, you will need to get a separate CAM for the PC DVB card.
Unfortunately, I am only familiar with pricing, online stores and where to get products in Ireland and the UK, so I am not sure what shop or online store to try in your area. Probably the best thing to do is browse through a shop that deals with satellite TV and have a look at any DVB cards they may have for sale. If the product mentions that it has a CI, CAM or common interface slot, then it will take a CAM. The CAM must be purchased separately. I am not sure if there are multi decryption CAM’s in your area (very common here in Europe), but if not, ask for a Nagravision CAM.
There are only a few features that vary when choosing a DVB PCI card. These are whether it has a CI slot (as I have mentioned), version of DiSEqC support, hardware MPEG2 decoding, LNB power and LNB loopthrough. All other features they may mention are standard such as EPG, software MPEG2 decoding, MPEG2 recording (or PVR) support, Time-shifting, Free-to-air, HDTV capable (in Europe at least) and so on since these are software based and come as standard.
Anyway, the main feature would to to look for would be a DVB card with a CI slot. The VisionDTV was just an example I came across as there are many others that can take CAM’s. If in doubt in a shop, ask an assistant at the shop to have a look at the product in the box to see if it really has a CI slot. If you come across one online, but are not fully sure, post the detail here and I will try to find out more info.
Hardware MPEG2 decoding is not necessary unless you have a rather slow PC such as under 1GHz. LNB power is only important if you plan on hooking up multiple dishes and DiSEQC switch or a DiSEQC motor. LNB loopthrough can be handy to connect both your PC and satellite receiver to the same dish, however you can still only use one receiver at a given time (not an issue with only one viewing card). Finally DiSEQC 1.2 support is only important if you plan on using a motorised dish.
In my opinion, shopping for a satellite DVB card is much simpler than for a TV tuner since the two main types of cards going are Free-to-air and ones with a CI slot.