PC World have added the pre-order UK pricing for Windows Vista!
Vista Home Basic is
£154.99 £179.99 inc VAT
Vista Home Premium is
£184.99 £219.99 inc VAT
Vista Business is
£250.00 £289.99 inc VAT
£325.00 £369.99 inc VAT
Windows XP Home: £140.95 Inc. VAT
Windows XP Pro: £220.00 Inc. VAT
And proof is over at PC World Windows Vista Pricing.