ATI Radeon x1950

I just purchased the Radeon 1950 crossfire for my new computer to run FSX. I have a AMD Dual Core 5000 processor with 2 gigs of memory. The video card is a pci-express 512 mB. Is there anything else I sould do or buy to run FSX to it's full potential, or anything I need to set on my video card to fun it to it's full potential? I thought about another gig of memory but would it make a difference?

A sound card if you currently use onboard sound. The Creative Audigy 4 is a nice mix of value and performance. It should improve the sound quality (d'ya think) but it will also free up your cpu a bit.
Obviously a joystick/yoke and then a nice set of speakers.
There's nothing quite like rumbling down the runway, full throttle, with a custom sound set and 300 watts of 7.1 shaking your brain.
I'm sure my neighbours disagree.

Use the latest drivers and keep that card cool!

As a warning, trust me when I say even with your above mentioned machine, you will not be able to run FSX full out and expect it to be above 10fps everywhere. I'd suggest if you max every setting out, you avoid cities like Seattle, New York, Tokyo, Chicago, etc.