Advice on finishing Window Installation

I Installed this window into my bathroom when I was renovating it, ripping out the Fibro and plasterboarding the Bathroom getting a good finish on the indide of the window was easy.
However I'm completly stumped on what my options are for finishing the outside.
It's been in for over a year now, and has not moved or leaked, but is an eyesore.
Bascially given the cladding around window what woudl be the best method for finishing this off. I'm just about to paint the outside of the house, so I think no more putting it off.

A point in the right direction would be great. Thanks.

There is only one thing to do. Trim it with a timber surround. BUT if you do only one and the other windows will get jealous and begin to feel ugly and unloved.

Cheers, I'll do that and hope the old windows don't get too jealous...