I personally would not consider getting a laptop with a celeron cpu. They may do the basic of tasks but when you ask a little bit more from them you will see why they are so cheap.
If you want a cheapish laptop with a semi-decent cpu consider a click here at £299. Add some extra ram and you should have a machine that will be head and shoulders above the celeron.
As to vista. If you trim some of the start up programs, it should boot faster than XP.