Home Built PC advice

What is the asking price? You can upgrade any computer if one cares to.
What will you be using this computer for?
What operating system is installed?

I did a quick check on prices and came up with about #450.00 to $500.00 new for parts. You should double check that. My understanding is Autodesk Inventor is a CAD program. All CAD programs like lots of ram. Which means Windows 7 64 bit so you can use more than 4 gigs. My opinion is this computer is the middle of the road system. If you buy it I would install at least 8 gigs of matched ram to meat your motherboard and cpu specs.

If you are going to start major upgrading like motherboard with a newly bought computer doesn't make sense to me. I would just add the ram and nothing more to that computer. If you so need or desire bigger and badder computer you either buy one or build one from scratch. It's easy step at a time.
1. How much money to spend.
2. What are my computing needs.
3. What are my computing desires.
4. How much growth for computer needs or desires do I want to built for.
5. Now the part many don't want to do, their homework. The research that it takes to buy or build a computer the way you want and or need.
In my opinion a $50.00 case with a unknown power supply with a mid range cpu and motherboard is no place to get carried away with major upgrades. I hope this will help you on your purchasing decisions.