light aircraft cockpit advice and which sim is better?

Hi im going to build a home cockpit. First I wanted to build an a320 I got all the plans but I don't have enough space in my room for it. I'm searching for a plane which is light and have more procedures to be done until the flight(its more interesting when you have what to do until the flight) I have fsx and x plane 10 but im not sure that my pc is enough powerful to run x plane 10.
Here are the specs:
Cpu: amd athlon 5800+ dual core 2.8 ghz
Ram: 4gb kingston
Videocard: amd radeon 4830 hd
Win 7.
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So can you give me advice with the plane and x plane 10 vs fsx for my pc

Thank you!