although I block ads out of principle, IceFire has a very valid argument, and besides that, the space occupied by the banner is otherwise not used.
Alternatively, instead of removing it (which could hurt HLP in he long run) there's another way to 'remove' it. It is also possible to rig the banner html (width=0 hight=0 ring any bells?) so that the banner is still downloaded, thus producing the 'impression' to keep the sponsor happy yet being invisible because of the htmlsizing.
OTOH since we spent 99.99% of our time at any other point on a page than the top, you prolly will hardly ever see it even if you do not make it 0x0 in size (thru html, not physically resizing the img)...