big difference?

[chelseafc2007]

alright guys ive just orderd a new pc from www.wired2fire.com who i orderd from as pczone and gamer have recomended them as good builders and use good parts,, which i hope is true have any of you guys have dealings with them b4.
the specs are
Diablo Xtreme
Case:SilverStone TemjinPower Supply:Tagan Turbojet 900WProcessor:Core 2 Duo E6700 4MB cacheCPU Cooler:Zalman Ultra Quiet CNPS7700-Cu CoolerGraphics Card 1:BFG GeForce 8800 GTX 768MB PCI Express (Check Case Dimensions)Graphics Card 2:NoneMemory:2GB Corsair DDR2 XMS2-6400C4 TwinXMotherboard:Asus P5N32-E SLI Plus Socket 775Hard Disk Drive One:400GB Caviar SE16 SATA 300Hard Disk Drive Two:NoneOptical Drive One:BTC DVD-Rom x16Optical Drive Two:NEC 4570A DVD-RWRemovable Storage:NoneSound Card:Onboard soundSpeakers and Headsets:None Monitor:NoneKeyboard:NoneMouse:NoneMiscellaneous Adapters (may require free PCI slots):None Software:None Operating System:Microsoft Windows Vista Home BasicWarranty:Collect and Return Warranty (1 year + 1 year labour only)

costs 1750£

my old comp is pent4 3.2
1gig ram
120gb harddrive
and allinwonder x800 g/card

will there be a big diff in speed? as ive been gettin big lag nearly unplayable in modern games .