Decent bike from 300-600

Hi All

I am looking for a bike to do mostly cross country, as I am going to bike around Europe for 3months but also for afterwards to do more off-road. Unfortunately my budget (300-600) is low but I have found a lot of nice looking bike but I am not in the know for what specs are better. A little advice would be much appreciated.

Trek 4300 D http://www.evanscycles.com/products/tre ... e-ec042069

Giant Revel 1 29er http://www.jejamescycles.co.uk/giant-re ... 73926.html

Claud Butler Cape Wrath 02 http://www.jejamescycles.co.uk/claud-bu ... 77234.html

Cannondale Trail 7 http://www.edinburghbicycle.com/product ... trail-7-14

Carerra Vulcan http://www.halfords.com/webapp/wcs/stor ... yId_165499

Merida Matts 40-MD http://www.tredz.co.uk/.Merida-Matts-40 ... _55241.htm

Bianchi Kuma 4700 http://www.tredz.co.uk/.Bianchi-Kuma-47 ... _57780.htm

Scott Aspect 640 http://www.tredz.co.uk/.Scott-Aspect-64 ... _56859.htm

Ghost SE 3000 http://www.chainreactioncycles.com/ghos ... -prod81701


Sorry about the length of the list this has been my problem it keeps growing and I dont have the knowledge to eliminate any.

Thank you in advance for the much needed help