Congrats!
I also received a Dell Studio 15 with almost the same config as yours a few days back. Upon boot up, the lappy showed an avg. of 25% cpu usage. I decided to remove Vista and install Win 7 and viola! cpu usage shows as 3% or less and ram shows up an avg. of 800mb
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PC Spec :
CPU : Intel C2Q Q9450 @2.66GHz
CPU Cooler : TRUE 120 (120mm Scythe)
MOBO: Gigabyte GA-X48-DQ6
RAM : 4GB G.Skill DDR2 @ 1066MHz 5-5-5-15
OS: Windows 7 RTM X64
Asus Xonar Essence STX
MONITOR : Dell 2209WA
HDD : 4 X WD 1TB BLACK
CABINET : CoolerMaster Cosmos 1000
GFX card : EVGA 8800GTS 512MB (G92)
VGA Cooler : Thermalright HR-03GT (92mm fan)
SMPS : Corsair TX 750W
APC Smart 750I
Logitech MX518
Razer Lycosa Keyboard
Mousepad : SteelSeries QCK (medium)
DVDRW: 2 X Sony DVDRW SATA