Motherboard: DFI Lanparty UT nF4 Ultra D: nForce4-Ultra, 1000MHz FSB, 4xDDR400(2x), ATA/133, 4xSATA/300, 2x16xPCI-E, 2xGigaLAN, 7.1 Sound, Firewire, ATX
$224
CPU: AMD Athlon 64 X2 4400+ CPU + Fan - S939, 2.2GHz, 2x1Mb, 800MHz - Dual Core
$825
RAM: GeIL 1Gb 400MHz CL2.5 DDR Memory Kit (2 x 512Mb 400MHz DDR RAM)
$145
Hard Drives: 200Gb Seagate Barracuda 7200.8 7200rpm Hard Drive - Serial ATA, NCQ - 5Y
$158
Floppy Drive: Sony 1.44Mb Floppy Drive - Black
$15
DVD Writer: Pioneer DVR-110D 16/16/8/6/8 DVD-ROM/±R/+RW/-RW/±DL Internal IDE - Drive Only - Black
$95
Video Card: Leadtek GeForce 7800 GTX 256Mb 16xPCI-E Video Card + 2xDVI/VIVO
$885
Sound Card: SB Audigy 2 ZS Sound Card
$164
Case: Antec SLK3700BQE Black ATX Quiet Medi-tower Case w/ 350w PSU
$134
Monitor: Benq FP91G+: 19" LCD (8ms) Monitor - D-Sub/DVI - Silver/Black
$595
Keyboard/Mouse: Microsoft Wireless Optical Desktop Elite
$127
Total: $3369AU (Quoted form an AU site)
http://www.secret.com.au/cgi-bin/computers/trialdb.pl
So as you can see, to add another video card u will need to upgrade your motherboard.. i would suggest to DFI SLI-DR which is $270, $50 more then the DFI Ultra D listed. Then its another $885 for the card.
If u want 2x1GB PC3200 Ram it is: $354
So total with both the extra video card,sli motherboard and ram is:
$4513
The differance between the 4400+ and the 4800+ is that the 4800 is only 200Mhz faste, and you could OC ur 4400 to 4800 speeds easy. 4400+ = 2200Mhz 4800+ =2400Mhz