Notebook vs Desktop

Hello, my apologies if this is in the wrong section.

I've been considering a Toshiba Satellite A215-S7422 Notebook, to replace my slightly outdated Dell Dimension 4700 and have been wondering how the notebook compares to the desktop in terms of speed and processing capability?

Notebook Specifications-
Processor
Processor Type * : AMD Turion™ 64 X2 Dual-Core Mobile Technology Processor Number * : TL-58 Processor Speed * : 1.90GHz Front Side Bus * : HyperTransport™ Technology @ up to 1600MHz
Operating System **
Genuine Windows Vista® Home Premium (32-bit)
Memory Size *
1024MB
Memory Speed
PC5300 DDR2 667MHz SDRAM
Display Size *
15.4" widescreen
Display Type *
WXGA with TruBrite® Technology
Display Resolution *
Choice Of: 1280x800, Supports 720p content
Graphics Engine *
ATI® Mobility Radeon™ X1200
Graphics Memory *
128MB-319MB dynamically allocated shared graphics memory
Hard Drive Size *
160GB
Hard Drive Speed
5400rpm


Desktop:
Processor: Intel Pentium 4 520 w/ Hyper-Threading Technology
Processor Speed: 2.80 GHZ
OS: Windows XP Home
RAM: 768 MB DDR2 -~PC-5300~- ( I think )
Main Board: Intel 915G Express
Data bus speed:800 MHz
Hard Drive: 40GB SATA @ 7200 RPM
Drive: DVD ROM
GFX Card: ATI Radeon X300 Series 128 MB DDR
Sound: SoundMAX Integrated 5.1


Also, Is the laptop a good buy for $700, which is occasionally marked down to $550?

Thanks

What would you like to use the laptop for? It should be fine for office use and surfing the web.