Best flight sim games for my Mac system?

[Admiral Beez]

Here's my iMac info:
Mac OSX 10.4.11
Processor: 1.8 GHz PowerPC G5
Memory: 512 MB DDR SDRAM
Machine Name: iMac G5
Machine Model: PowerMac8,1
CPU Type: PowerPC G5 (3.0)
Bus Speed: 600 MHz
Built In Sound Card: Burr Brown PCM3052

Graphics:
GeForce FX 5200:
Chipset Model: GeForce FX 5200
VRAM (Total): 64 MB
Vendor: nVIDIA (0x10de)

Based on this system, what are the best flight sim games available for my Mac? Most of what I'm finding online needs more VRAM that I've got. Thanks.

 

[Admiral Beez]

If I wanted to increase my Video RAM, do I need to take in the computer to a Mac store, or can I do this at home?