has anyone tried a 3rd party power adapter? i have a MB alum and correct me if i'm wrong, but it needs 60w - right? is there a downside to this? i just need something for the family, so i don't have to keep moving the OEM charger from the office. http://cgi.ebay.com/60W-MagSafe-Pow...arger-NEW_W0QQitemZ270332037228QQcmdZViewItem or http://cgi.ebay.com/60W-AC-Power-Ad...in_0?hash=item27a9d045f3&_trksid=p3286.c0.m14 thanks in advance!