Most browsers including things like, you know, an address bar and tool buttons don't equal 600 pixels tall.
I use MyIE2, which has a ton of toolbars and shit. It's about 133px tall.
The start menu and status bar in MyIE2 come out to 51px (thereabouts)
So, about 180px tall.
600 - 180 = 420px
Even at 800x600, we're talking 420px of viewing space available. At 100px, an image leaves 320px of open viewing area.
Now, even though I've just showed that Makk is just being facetious (probably), I agree with the point of view. Huge sig images are, if nothing else, obnoxious. STOP IT, FUCKERS!
---
Do you want ants? Because that's how you get ants.