Tbh I did think about an Macbook as my next computer,but just can't justify the cost.I was /am looking on the lines of a desk top replacement...17" screen, a 17" Macbook is over £2000 ...no way am I am prepared to pay that.I can get a very good spec Dell for around £700
This suggestion is only justifiable if you have some reason for wanting a Mac, but have you considered a Mac Mini? A lot closer to PC prices, and you can upgrade the monitor etc independently, or re-use your existing one. Pretty basic though, they're essentially built out of laptop components and don't even have an internal optical drive these days.