Advice on moving from two servers to one w/ VMware

Server Config
1

I currently have two dedicated servers. Here are the specs:
Server 1:
2x Xeon 5450 Quad Core
8gb ram
2x 146gb 15k SAS drives

Server 2:
2x Xeon 5520 Quad Core
12gb ram
2x 146gb 15k SAS drives

I currently use server 1 for running php, serving files, and xcache, and server 2 for mysql.

The problem is, this is probably more power than I currently need (and am paying too much for it) and would like to consolidate to one server running ESXi, splitting the two.

Question - how would you set it up? SAS drives in RAID? How much ram total, and how much allocated to web/database? Does splitting one server even make sense in this application, or should I just get two smaller servers?

Some insight would be greatly appreciated!

2

I’d definitely keep separate database and application entities, whether that means two virtuals on one server or two smaller servers wouldn’t make much of a difference, in short, if one gets compromised, it shouldn’t have direct access to the others data.

Now as to how much you need, you’d really want to install some sort of monitoring tool (such as munin) to determine that. Let it graph out what they are currently using for a week and then get 30%-50% more than what it averages.