How to make smooth outlines

[Kasualty]

I have an image and increased its size from 150 × 135 to 2000 x 1803. It was the only image I could find.
The problem is, now the outline of the image is jagged. I want to know how I can make a smooth outline of the image. I've been using the pen tool to trace the outline by hand, but I was wondering if there was an easier way.

This image is for a shirt I'm designing, so it needs to be smooth.
I'm using photoshop CS5.

[SoConfused]

The pen tool is probably your best bet.

[Daverom]

redrawing it is literally your only option unless you can find a bigger picture.

[Kasualty]

preciate it