i've had 2 micros (one was stolen) and neither had any headphone jack problems. i have, however, heard that it's a notorious problem with the micros, so i know how you feel. i probably would not have boughten them myself if i have known about it.
if you don't want a micro though, check out the iriver h10, it's also 5gb, has a fm radio plus a color screen, which is nice. although, i highly recomend you get a 20gb, when i bought my micro a few months ago i couldn't fill half of it, now i already have over 10gb of music, and i really regret buying a 5gb mp3 player. if you decide to get a 20gb, for sure get the iaudio x5. color screen, plays video, really really nice player, my friend has one.
if you don't want a micro though, check out the iriver h10, it's also 5gb, has a fm radio plus a color screen, which is nice. although, i highly recomend you get a 20gb, when i bought my micro a few months ago i couldn't fill half of it, now i already have over 10gb of music, and i really regret buying a 5gb mp3 player. if you decide to get a 20gb, for sure get the iaudio x5. color screen, plays video, really really nice player, my friend has one.