SSTSim Concorde or VRS F-18

Hello. I'm a bit bored to fly today's typical commercial jets. I wanna fly different situations, so I'm interested in buying SSTSim Concorde or VRS F-18.Of course, they aren't comparable. I'd like to ask you some questions of them. My PC is old. The spec is following. CPU:Core2Duo OCed to 3.0GB. OS: Vista 32bit. Memory:3GB usable. Graphics:9800GT 512MB.1. Frame rate of VC. I prefer VC and want 25fps at least on my pc.2. Refresh rate of VC Gauge. Normally, that of FS9 seems limited to very low. I don't want to see HUD stuttering.3. Navigation. I don't want to waste my time to input coordinates of waypoints to CIVA INS. But I also don't like default GPS. Can I use a 3rd party navigation system with them if I bought it?Thanks.