That's a bit curt, Martin, but we can ignore it, if you like!
First off, have you built before? Sounds as if you have.
Second, what's your experience with flight sim? Do you intend to go the P3D route at all?
Finally, on the hardware, I'd check with Tom's Hardware ( http://www.tomshardware.co.uk/ ) before buying any HDD/GPU/PSU. There's a lot of good advice there. For example, look for a hybrid SSHD, they're up to 3 times as fast and perfect for gaming.
Hope that helps.
You're Welcome!
Cheers - Dai.