if your only wanting the pc tower then id agree with the above, if how ever your wanting the whole package, screen, keyboard etc then it can work out 200-400 cheaper depending on spec.
Have a look on dells site at what kinda spec your after http://www1.euro.dell.com/content/to...186&lid=121454
Then source some parts on here http://www.ebuyer.com/

And then do the maths on which is cheaper, for YOU