Here are some tips, that will help you a bit:
- I run 400 sites on IDE drive with no problems for several years
- What about back up? What will happen if your disk fails? According to your specs you will loose the business.
- you will not need all that CPU power from the begining
So what you need, if your are on small budget:
- DUAL CPU MB with 1 CPU, upgradebale to 2 CPUs
if you run all services on a single server (web, mail, sql) than
- 512MB RAM upgradebale to 1024+ MB
- 1 SCSI primary drive + 1 IDE backup drive
Every night or so you update files on your backup drive. Do it at night, when server load is minimal. IDE drive can easily generate
10MB/sec (80 mbps) - it is much more than your network is capable to handle or your ISP will allow you to allocate
The more memory you have in your server the less critical HDD speed becomes.
On the other hand SCSI is more reliable and faster, and uses less CPU resources, so if you can afford - use SCSI.
If you have $10K - $12K to start with: build a server for each service: web, mail, sql, dns, control panel, log. You do not need fast expensive servers for mail, log and dns, but they must be reliable.
If you have any further questions - post here and I will try to answer and help.