busyDell's lowest price is back to just under £200, with more memory and a larger disk than before, albeit not including a monitor. But if you're upgrading, you've already got one of those. (And if you're not, Dell are not the best people to buy one from.)
e-value code 305-D04111.
Update: to get the price down to £199.82, change the warranty to '90-days collect and return', rather than 'three years at home'. If it's still working after 90 days, it should keep going for years anyway.
This price will doubtless be different next week. Dell are like that.
Let's see... yep, lose the warranty = down to £199.82