Displaying the number of registered users to a website

Question

I am building an online game much like Mafia Wars. I was thinking of displaying the number of registered users on the home page, but then I thought:

"What if a new user sees that the total number of registered users is 5?!" :D

That would be too embarrassing to my still growing game. Then another thought came by:

"Why don't I display 500 instead?!" ;)

Nobody would know if there is actually 500 users registered to my website unless of course they start actually playing and interacting with other players.

However, I just have a feeling that this isn't ethical. What if this generates a negative publicity to my website?!!

What's your opinion should I fake the number? or should I honestly display it? or should I wait till I have 1000 real account then start displaying the number?

And most importantly is this legal?! :D