What's all this crazy talk about the video card, Hunter? Have you ever used a flight sim or done ANY gaming? The better the video card, the better the gaming experience. It has been proven over and over.
The only time adding more RAM is slower used to be in WinNT after adding more than 2 GB, it took NT more resources to manage the RAM, slowing down the system kernal. In Win2k or XP, more is better, especially with a slower hard drive, because you will not be using the swap partition as much with more RAM. RAM is cheap, get as much as you can afford and you can always add as many DIMMs as you have slots.
As far as integrated sound and NIC, they don't use shared memory like the video card, because the video card uses RAM to display the screen. All the NIC and sound hardware is built into the mother board just like it is on a PCI card. If you don't like the built in sound or NIC, add a better PCI sound card or NIC. You can get a 100BT NIC for around $20, and a top of the line sound card for $200.

Hunter, think before you respond.

PaPa, your computer will be more than satisfactory for the current generation of simulators and 3-D games. Purchase Real Flight and stop wasting you time listening to Hunter's drivel.