The aliasing on text will vary depending on:
Operating system (Windows 7, Windows XP, Mac OSX, Ubuntu etc etc etc)
Web browser (Internet Explorer 8, Firefox, Google Chrome, Safari etc etc etc)
User specific settings in both the web browser and operating system.
When you do mock-ups in Photoshop it is best to either ignore the smooth text or use "none" in the alias option, but you will not be able to accurately replicate how the text will display either way.