site structure and search efficiency?

[qwertyjjj]

The way I understand it, you create a worksite for a group to collaborate around (WSS or MOSS).
In MOSS you can search across worksites.
In WSS you can only search in the same worksite.

So to create a similar hierarchy in WSS, can't you create a top level worksite and then say 10 subsites, each with another 10 subsites?
Are there any concerns here with search efficiency?

Thanks.