I'm sure my R5 has 512 nVidia 9800GT DDR2. I'm planning to use it for FSX with 4 LCD monitors. I could only find in the neighborhood a 1Gb nVidia 9800GT DDR3. SLI is out of the question anyway because I heard that FSX doesn't kind of "agree" with it.
Alienware Aurira R5 specs from the dealer:
Hard Drive Sata
Hard Drive Capacity 250 GB
L2 Cache 2 MB
Manufacturer Name ALIENWARE
Manufacturer Part Number PC-AURORA-R5
Memory Size 2 GB
Memory Type DDR2
Network Dual Integrated Gigabit Ethernet RJ-45
Operating System Windows Vista® Home Premium 32 bit
Optical Drive Type 20x Dual Layer DVD Burner (CD-RW/DVD±RW)
Processor Speed 2.7 GHz
VGA Controller 512 MB NVIDIA 9800GT
Hope this helps clear up things. Thanks.