[alug social] Double glazing recommendations?

I'd hoped I'd never have to ask this, but can anyone recommend any double glazing people in or around Norwich? I'd really rather use someone on a recommendation than have to risk getting a heavy sales pitch directed at me. (There's a Linux link here; my sensible brain cell has kicked into action and said I can't have a new laptop until I finally get the windows sorted out. A Toshiba Portégé R200 is calling me I think.) J. -- Revd. Jonathan McDowell, ULC | Death is a nonmaskable interrupt.