Dell usually posts all its technical service manuals which detail how to completely disassemble/assemble their laptops online. Those manuals make it pretty easy even for a absolute novice to see how to take them apart provided they can hold and turn a screwdriver.
HP/Compaq also posts lots (though not all) of theirs at their support site as well. You really have to look around for Acer/Gateway/eMachines stuff, though, as they seem to treat it like classified material (often, I've found them via international support sites like ACER Panama, etc. via Google where the employees aren't as strict about disclosing them).