The Collaborative International Dictionary of English v.0.48:

Advantageously \Ad`van*ta"geous*ly\, adv.
   Profitably; with advantage.
   [1913 Webster]

WordNet (r) 3.0 (2006):

advantageously
    adv 1: in a manner affording benefit or advantage; "she married
           well"; "The children were settled advantageously in
           Seattle" [syn: well, advantageously] [ant: badly,
           disadvantageously]