New pc-decision...

hi,
I was looking for a new pc that i might buy,and look at these two offers i found from dell:
1)Advanced Multimedia
Dell dimension 9150
1099€
Intel Pentium processor 4 640 with HT Technologie
(3.20 GHz,2mo L2 Cache,800MHz FSB)
Authentique Windows XP family edition
1024 Mo of memorie PC-4200 Bicanal DDr2 533MHz
Motherboard 500 Go SATA Stripe Raid 0
19''Dell flat screen
nVidia GeForce 7300 Turbocache 256Mo PCIe
DVD+/-RW 16x Burner
8 USB 2.0(1 interne),3 PCI
1 PCI-E 1x, PCI-E 4x,PCI-E 16x
1 year garantie
Media Flash card reader 13:1
Bonus:for 1€ extra a 725 Dell Printer

2)Gaming
Dell dimension XPS 600
1449€
Intel pentium processor 4 640 with HT Technologie
(3.20 GHz,2mo L2 Cache,800MHz FSB)
Authentique Windows XP family edition
512Mo Pc-4200 Bicanal DDR2 533MHz
Motherboard 160Go SATA
No screen included
nVidia GeForce 6800 PCI-E 256Mo DVI/Tv exit
DVD+/-RW 16x Burner
8 USB 2.0 Ports, 2 IEEE 1394 Ports, 4 PCI slots,
1 PCI-E 1x, 1slot PCI-E 16x
1 Year garantie
Bonus:double Memorie for 1€ extra

Now can somebody please tell me why a pc that has a 19'' screen cost's 399€ less than a pc with a worse video card,less memory and no screen???