As far as I know, with laptops it's either not possible or at least damn difficult here
desktop pcs are slightly easier to find, though they're not everywhere either. My best bet would be to try and use web search engines to find a store with laptops without preinstalled OS, but you might have to give up and buy one with Windows. Try to buy an XP-one or something, they're cheaper
Btw. IBM laptops are nice. Well, not exactly all of them, but there are a few models that really are a whole lot better than some others..