Ok, so just a few hours ago, I, for the first time in my life, got a chance to play through an actual cranked up tube amp.
Holy shit, teh hawtness. Played on my cousin's Kendrick and his Princeton, and the tone was absolutely eargasmic.
Emulations I've tried do not even come close to the real thing.
HOWEVER, I'll have to dissagree with PriZm's assertion that you can't get good solo distortion from software. Amplitube 2, though it may not sound like a REAL tube amp, can sound absolutely fantastic on leads.