Personally I would look for a second hand Planet-X Zebdi. Just have a look on ebay for a full bike build. Or, alternatively;
Buy a second hand Zebdi frame for around £100.
Get some second hand forks like pashleys - £30-40
Buy new wheels, I reccommend Hope hubs (XC or Mono) on mavic D521, buy from Tartybikes and get an ace wheel build from Tatry himself - Around £200.
Buy a pair of Magura HS33's - try ebay, they go for around £60 a pair.
For cranks, I would reccommend some second hand middleburns preferably in good condition - about £70.
Then just buy some normal parts and this should come to about £500-550.
The zebdi, in my opinion would be a much more street orientated bike, while still being a worthy frame for the occasional competition. It just give you alot more options when riding street, like manuals. And as everyone knows manuals are the coolest move ever, and ever will be.