Enlarging and smoothing

I'm having trouble successfuly enlarging a small animation of mine (50x50 px).
When it's small, the way I original drew it, it looks fine, but when I enlarge it to a bigger size, my picture is boxy. I need a way to smooth out the lines that were originaly just 1px wide.

p.s. If you need the pictures to know more of what I'm talking about (or for natural interest ;)) you can email me at [email]Yacovitch@homtail.com[/email]

p.s.s. I'm loving your tutorials, keep them comming

Yea, when you enlarge images of a small resolution (like web graphics) Photoshop has to make up new pixels. It does the best it can and the result is a little blurry, but (depending on how much you enlarge) definitley looks pixelated, or jagged.
To avoid this problem, I'd suggest going about it the opposite way- create your animation first at a larger resolution (200 x 200 px- or whatever). Then you can shrink the image as needed. This way it will look acceptable at both sizes.