Casual use or professional. If this thing is dedicated to working in those programs I would take the professional graphics card just to have the driver's capabilities. Though I would probably spring for a little more then the K620. K2200 is a decent card.
To just learn you don't really need an expensive card. The more powerful the card the faster it will be able to complete rendering jobs. Certain types of math are restricted on the gaming cards. They can still do it, but without the optimization they can take longer. (Or it will just use the CPU to do it)
K620 gets Autodesk's endorsement for 3D Studio Max 2015 (It will still render on other cards, just not as quickly)
Cinema 4D is open GL and should operate on any GPU
Sony Vegas is open GL and should operate on any GPU
Slightly faster for $20, motherboard is a lot cheaper to make up the gap. You can change it back if you want. Also changed the SSD and power supply for higher quality parts.