LordMalis did specify a 'medieval fantasy world'. Straight medieval I wouldn't go for, but with a few conditions on the fantasy part, I would consider it.
Conditions include;
[*]no bubonic plague
[*]magical or herbal medicine advanced enough that nobody dies from minor cuts or broken bones
[*]no sadistic dictators or nobles with the legal right to kill peasants on a whim
[*]magic, unicorns, elves, dwarves, et al.
[*]magic advanced enough to meet or exceed modern conveniences (at least health, water and sewage systems widely available), without the disadvantages (like pollution). Everybody else wouldn't necessarily need to have full access to magic, but of course I would. <img src="/ubbthreads/images/graemlins/badsmile2.gif" alt="" />
[*]I'd have to be a mage, of course (or what's the point of a fantasy world?)
[*]I'd have to be powerful enough I could not get knocked out and chained to a post in a factory cranking out charms
[*]My ambitions are modest, though. I'd settle for being the most powerful human mage; if a couple elves or elementals were slightly stronger that would be ok.
[*]probably a few more, as well....