How many sites do you think a RAQ 550 can handle, with light to moderate usage on average? *I know this is relative, but i'm just wondering how many sites a 1GZ server can handle, as opposed to the 450GZ raq 4. I generally do not put more than 100 to 150 on a raq3/4, so will the raq 550 be able to handle more sites?

The hardware is much more powerful so he'll be able to handle more virtual sites.

How many?
Depends on the load...
kind of pages,... (PHP, MySQL,...)

But, he may be as powerful as he is, I won't ever put more than 200 sites on it...

Also depends on what kind of traffic and resourses these sites use.