installing ColdFusion and database

I just went through some of this, and using a single server is still an issue.  We run with a couple of CF servers and a single MS SQL server, but have a client that we wanted to isolate onto their own system.  We put both MS SQL and CF onto a single large (dual Quad CPU + 16gb memory).  Although SQL runs like a scalded {insertanimalnamehere} CF isn't much faster.  We had to tune the max memory for both MS SQL and Cf so that they both didn't try to take over the system. 

Basically, you have two pieces of software that each try to handle their own CPU scheduling and memory management.  When they are alone on a system then it's just htem and the OS, but put them together and now you start to have situations where they each think they have a resource available (cpu, memory), and the OS ends up trying to sort it out for them.

If I had to set that box up again I would seriously consider virtualizing it into two boxes to keep them out of each other's hair.  Or just getting a second box for CF, which doesn't need much in the way of disks and doesn't need to be a beefy as a database server.

Have always installed CF on a different server than the database. It's

generally a resource-allocation issue: let high load hit the web server

and let difficult data requests hit the DB server. Assuming you have a

good solid connection between the 2 servers, the overall performance

benefit will usually outweigh the slight uptick in network overhead.