Need Help on best Video Card for FSX

Hello, Just want some advice on which video card to purchase to run fsx better. My specs for my HP a1630n are:AMD 64x2 Dual Core Processor 5200+2 Gig of RamNvidia GeForce 6150LEAs you can see I'm still using the card that came with the rig 2 year ago. I'm currently getting between 5-8 in high detailed cities, and 10-18 everywhere else. Im running sliders on Medium-Low and I use real-world weather with 3d clouds set to low. I run 100% AI traffic, as i like the feeling of realism. All in all i can pretty much fly into any aiport with maybe one or two stutters approaching KEWR or KLGA. Taxiing, only Newark gives me pauses once in a while. After reading tom's hardware; it seems the 8800GT is the way to go? I have a 380W PSU. So would i need to upgrade it to run the card? Any suggestions welcome.PS: I'm willing to spend up to $300 for a card.