ok why do you guys say that dell and clevo offer mxm upgrades..lol...those arent even mxm capable laptops. and there is a store where you can buy its called mxm-upgrade.com
there are three types of mxm ...I II and III. basically III is the best since it can handle all three types and the more powerful graphics cards. but, having a laptop that is mxm III doesnt necessarily mean that youll be able to upgrade to any other mxm III card....THEORETICALLY YES, but the manufacturers of the laptop dont really abide by the "rules" and they create their cards that could require any amount of power and expel any amount of heat.
its really trial and error...you dont know unless you try it. theoretically you should be able to upgrade an mxm laptop with any other mxm card that fits within the category...but mxm hasnt really hit the market yet....more mxm cards are being released and that website ig ave you should have them. there are also various vendors in europe that sell mxm cards...i found one site with the 7800gtx mxm III card....i might try it in my m5700...it may or may not work....it is a minor chance that it would ruin my pc....but it could happen