Thanks Las
Thanks for that. At the office I have a 24inch LCD I use and use the portabilty to get out of the office. The weight of the 17inch would be a concern for me.
Following a conversation with the Australian Graphisoft suport I have upgraded my specs. I was wondering if you could give you opinion on this toshiba. 
http://www.mytoshiba.com.au/products/computers/satellite/p850/pspkfa-02c001/specifications
CPU	Intel® Core™ i7 processor 3630QM (2.4GHz - 3.4GHz, (Turbo ,4 Cores) 1333MHz FSB, 256 KB per cache, 6MB L3 Cache)	
Operating System	Windows 8 (64bit)	
Chipset	Intel® HM76	
Screen Size	15.6" Widescreen HD LED Backlit Display (1366 x 768)	
Resolution	1366 x 768	
Screen Aspect Ratio	16:9	
Memory	8GB DDR3 (4GB+ 4GB) (1600Mhz)	
RAM slot allocation	Both slots used. Total memory expandable to 16GB	  
Storage	1TB (5400rpm) with Toshiba HDD Accelerator	
Graphics	NVIDIA® GeForce® GT 630M 2GB with Optimus + Intel® HD Graphics 4000
Thanks Again.
Warwick