I thought you were on about replaceable heads and not rebuildables..Yeah I'm going to go back to a vivi nova I think, thanks all.

As I said, your best bet if you don't want to go rebuildable is either the Protanks of some kind or the Aspire BDC's.
Their the best of the 'replaceable head' lot
http://www.safercigs.co.uk/Aspire_bdc_Pyrex_Nova/p705283_11105194.aspx
Thats the Aspire Vivi Nova different head to the original one, but the Aspire heads are supposed to be really good. (their dual coil)