Well, whether it happens automatically or not depends, I guess, on their browser's security settings.  I get asked if I want to install the Comet Cursor, but I think that the "Enable Install on Demand (Other)" option in IE might enable the applet to be installed without consultation with the user.  If that's the case, I suppose s/he'd get "infected".  Curmudgeonly old people like me can be pretty irritable when stuff like this happens.  And I have heard of Comet Cursor causing some fairly serious problems on some computers, mostly by causing crashes because of video driver issues.  I've seen some sites where the public was warned about the cursor and offered the explicit chance to avoid installing it.
- Collin 
Edit: BTW, cute site. I hope to get back to it and do some reading.