I'm sure this has been asked before, so excuse what's probably a novice question. I'm a competent age group runner (2.53 marathon last year at 47) who for various reasons has decided to shift focus and is moving into X-terra this summer.

I'm obviously comfortable on my feet and my swimming is what it is (I'm working on it in the right way) but I barely know where to begin with finding an appropriate bike.

I have to say by nature I'm quite competitive so the plan is to push myself and while this summer I'll keep focussing on running (because I can compete there) while I "learn" Xterra and get my toes wet with a few trial races, by next summer I'd like to have made some strides. But as now, I'm still bumbling along the trails on my wife's ten year old unbranded mountain bike. What do I do? Right now, sorting out the bike question is my biggest problem.

I don't want to spend a fortune (well, I do, but I haven't got a fortune to spend) and where I'm lost is not so much brands and models (though I'm lost there, too) as do I get a hardtail or a full-suspension, downhill bike or an X-C, what components do I search out, or whatever. It's all double-dutch to me. In short, for Xterra, where do I begin?

If it changes anything I am _base_d in the UK and I really need to get this problem addressed without delay. Thanks for any help or advice you can give.