I'm in the market for a quantity of computers, say 50 every three months or so ongoing. I would like to purchase from somewhere that doesn't put any OS on them so as I can install Ubuntu. I'd like that 'service' reflected in the price - that is, I'd like the most bargain basement PC available. I'd like Dell machines to be honest. They do Vostros for £160 plus the dreaded, which if you took the Vista infection away might be more reasonable. However I fear they will just giggle when I ask them to supply without an OS...

So, does anyone have any experience they'd like to share of purchasing quantities of machines within the UK?