Ad server/db server separate or all-in-one

I'm starting a type of internet ad company. The 3 main things I want to do are: chatting, ad serving, db queries.

My question is about how many servers I need to support a given load of users. Would 3 servers (one per task) be overkill for, say 100,000 ads/day? Or would one good server be sufficient for all 3 of those tasks.

I know I can buy/build a server that is cheap or expensive, but try to answer my question considering a dual P3 600 box (like the one I already have).

Thanx.

I think while 3 servers maybe a bit expensive, more is always better with what you want to do. However I think that an optimal setup would be to have 2 servers, one for the database and the other one for the chatting/ad aspects of your operation. However there is also the fact on how many people would also be chatting. If you are expecting over a couple thousand users all chatting at the same time, then a dedicated chatting server would be best.

Yeah, I think I'll be using 3 servers. While one may work for a little while, we'd soon find ourselves upgrading to 3 anyway.