Sizing An OLAP Server

Hi there,

We are experiencing some contention of resources between our RDBMS and our OLAP environment; both SQL2005; so we are going to put the OLAP side of life onto another seperate box. Therefore I need to work out what sort of requirements we are going to need; and this is where i have no idea.

I have had a look at the HP sizers, however this is looking primarily at normal RDBMS setups rather than specifically for OLAP. Is there any specifics that I need to consider/nail down before working this out?

To give you an idea:
We currently have 210 million rows in our main fact table, and each row is averaging about 330 bytes
The size of our current OLAP database is only 4GB
It appears as though we are currently getting anywhere between 6 and 20-30 concurrent users

Considering the above; I would have thought a dual core cpu setup (maybe x2) with 8-10GB of ram would have been the ticket?
Now I have done a server sizing exercise for a normal SQL2005 installation; considering temp db on seperate spindles to the log and database tables etc; but what sort of considerations do I need to do for a server running SSAS?

Thanks in advance for any assistance anyone can offer on this front

Regards
Troy