Hi, Gluk Schmuck. It's a nice sig, over there.
According to the
forum rules, your signature must not exceed 35kb in size, 400 pixels in width, and 125 pixels in height.
So, if your Flash signature is smaller than that (which I think it is, since you haven't used any picture) I guess it's ok to use it.
The flash plug-in is very common nowadays, but people who don't have it installed in their browsers won't see your signature banner, though.