Which is ok if you are using it as a small icon on a website, but when you want it printed on a t-shirt it's looks like you need new glasses. So I want to explain a few steps I used to create a newer version which still looks like the old logo but is scalable. I use Inkscape a lot and for this problem I used a very useful feature called 'Trace Bitmap'. When you apply this without changing the settings you get a vectorized image as shown below.
Wait, what?! That looks terrible. Ok we have perfect black shapes that we can modify, scale, change color but it doesn't look like the old image. In the original image we could recognize straight lines or perfect circles, but in the process of vectorizing the image it failed miserably. In cases like you this you have do a lot of work to fix what the tracing can't do. This takes patience and practice. Sometimes removing a couple of point that define a line can already help a lot, but in this case I had to redraw certain parts of the image from scratch. For example replacing the head of the volleyball player with a circle. But in the end the result was satisfactory as you can see below
If you're really picky (like me) you'll notice small differences between the original drawing and this new version, but you've got to admit that for a lot of purposes vectorizing is so much nicer.