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I wanna get one of these sleeves http://www.amazon.co.uk/exec/obidos/asin/b00081rrvq/ref=ord_cart_shr/202-9527555-4889400 or something similarmy laptop is the advent brand and measures 11 inches wide..what size case would i need? if i got a 12" case would it be big or does it need a bit of extra room to fit? thanks!

You need the case to be a bit bigger take your laptop to currys they have a big range.