I agree with the above,the Cannondale has had a lot of parts replaced,so it's probably had a fairly hard life too.You won't get a bike that combines full on downhill and crosscountry,so either pick one or the other,or get an allrounder.Your choice will come down to budget eventually,if you want to buy secondhand ,the sellers on here are generally much more reliable than ebay.I'd recommend you go to Wheelbase at Staveley,and have a good look at what your money will get you new,it will also let you work out what size frame you need.If you need any more advice,just ask,there's always lots available here,some of it worth having.
Ian