Wordpress and Server load issues

[LD]

I want to do lots of niche specific blogs which will, if i understand the way this works, require multiple installs of Wordpress.

I use virtual hosting, and was wondering how many Wordpress blogs I can run before I start to be a problem for my hosting company...?

btw, I also use a a couple of other scripts for managing blogs and and running a linklist (blogs automater and dragonlinks).