At present Lenovo laptops seem better value and better built than Dell, and have a wider range available with Win7 Pro
for instance see these, which are all "factory downgraded" to Win7
Notebooks | HP | Lenovo | Samsung | Toshiba | Acer | Asus | Notebooks from Cleverboxes
FYI - Cleverboxes are where Tesco source their computers for resale