I'm curious in knowing how far I can extend my server (how many sites I can host, etc).

Thus, I'm wondering if anyone knows how server load translates to hits/visitors.

If it helps, I have 1Gig ram on a 2.4Celeron.

For instance, is there some ROUGH translation, like 400 requests=.5 load or something, or is it completely variable based on time?

It is pretty variable really. Pure downloads do not translate to heavy loads but if there are processing involved like with scripts, programs and database, it can tax the cpu lots.

It all depends on the type of request, what the request is doing and things like that

More with static sites and less with dynamic sites.

Would it then be less taxing to have news/articles/1.html and have a new page generated each time; I should instead generate news into news/articles/news.php?=1