Well as far as I can tell you don't really know what you're doing.
For one, two of the same video card in SLI does not equal twice the processing speed. And that motherboard you have selected does not have SLI capabilities (as far as I know) meaning one of those cards would be useless. And XP Pro I think only supports 2 gigs of RAM.
Watch What you say without research.
The Asus Deluxe Wifi Supports SLI Capability's.
Want Proof?
The maximum amount of memory that can be supported on Windows XP Professional is 4 GB.
However,
The virtual address space of processes and applications is still limited to 2 GB unless the /3GB switch is used in the Boot.ini file.
The /3GB switch allocates 3 GB of virtual address space to an application that uses IMAGE_FILE_LARGE_ADDRESS_AWARE in the process header.
This switch allows applications to address 1 GB of additional virtual address space above 2 GB.
To edit the Boot.ini file in XP too allow for more ram is simply done using
[boot loader]
timeout=30
default=multi(0)disk(0)rdisk(0)partition(2)\WINNT
[operating systems]
multi(0)disk(0)rdisk(0)partition(2)\WINNT="????" /3GB
For Vista, 4Gb is the maximum for x86 processors without any modification (EMT64 etc.)
x86 is another term for 32 bit processor.
SLI Shares out the load of graphics processing, taking the load from one GPU and sharing it among two.
Just one 8800GTX Ultra would be insane to run games, but two? Thats Mad.
So Jealous.