Acer Aspire 9920G

[SHANE34]

My brother is leaving the UK in a few weeks he is selling his Acer Aspire 9920G

I have the chance to buy his laptop for £800 , might even sell my Dell 1720 , what do you think

Vista Ultimate
Acer Aspire 9920G
Optical Drive:HD-DVD
Core 2 Duo T7700 2.4GHz
4GB (MHz):667
HD Capacity:2x 250GB
Graphics Card:NVIDIA GeForce 8600M GT 512
20.1" WSXGA
1680x1050

How much is my Dell 1720 worth