I have been studying Russian with a native speaker on Skype for about a year now and I must say it's great! No need to get out of the house when it's raining ( I hate rains! X((( ) or when feeling lazy :P
I think everything depends on how good you are at languages... If you're highly motivated, you can achieve a lot in a 5 month period.
Anyway, my tutor is now starting her own website, so I hope she can help you as well! www.languageme.co.uk