How many servers do I need?

My initial suggestion would be two, low to mid grade servers.  I would have to ask you the following questions before I could give you a detailed answer;

1. How much network 'Down Time' can your business afford?

2. What kind of budget are you working with?

3. Who will provide your network support?

4. Do you intend to use a domain or workgroup?

realistically, we could afford a possibly one day - MAX of down time. Ideally, no more than a few hours at best.  I am prepared to spend upwards of 20K for the servers, routers, lines, etc. Perhaps my estimate is too low? Support will be outsourced initially then brought in-house after 3 -5 months.  I'm not sure I know the difference with regards to 'domain' or 'workgroup' Again, please forgive my ignorance. I'm your typical management guy, not a systems guy.

Thank you for your feedback. It's truly appreciated.

I'm going to start off by assuming that you intend to use a Microsoft server operating system like Windows 2000 or 2003 configured as a domain. Domains use 'centralized' security whereas workgroups use 'decentralized' security.  In other words, in a domain, all user accounts and resources reside on the server and access/permissions are governed by the network administrator.  This is by far the best way to configure a business network - even one as small as yours.  Since all logons are controlled by these servers (known as domain controllers) you will want two servers on your network for redundancy.  If minimum downtime is your desire than the word redundancy is your best friend!  Other reasons for reasons for having two servers include load balancing of network services (application server/print server/file server) and future growth(web server and email server).
You would be fine with a couple of PowerEdge 2600 servers and I would highly recommend looking at the Dell refurbished site - they are much cheaper and usually come with the same warranty.  Two comments on these servers from experience;
1.  Get it configured the way you want it (taking into account any planned future growth).  It's cheaper and easier than doing major upgrades later.  Recommended server configuration would be: redundant power supplies, RAID controller and at least 3 hard drives - even better if you can afford to fill the server with six hard drives.
2.  Buy the extended warranty/on-site support - the longer the better.  Your future IT staff may or may not be experienced server technicians but it's very comforting to have that warranty/support when the server crashes - not to mention the four-hour expedited parts delivery.

Don't forget to buy a good uninterruptible power supply for the servers - APC Smart UPS 1500 would suffice for a couple of Poweredge 2600s.
 
Good luck,
Bill...

Wpalwumbo: Can't begin to thank you enough for the information. You've been a great help.

It really depends on what you are doing with the server.  What are the applications?

My company is a consulting firm and we handle small businesses.  Some clients have 1 server, some have two.  You can go with RAID, but that's probably overkill.  You can mirror the servers, but that's overkill also.

Downtime is a consideration, but we use DELL equipment and it's reliable. 

Make sure you have a SMART UPS, on the server(s), this controls power fluctuations.

Please post some more details and we'll help you out.

At least 2 - I wouldn't place all of your eggs in one basket by buying 1 large server.

1 server for your domain controller (4 hard drives - 3 RAID5 and a hot spare if a drive fails)

1 server for your file/print. (4 hard drives - 3 RAID5 and a hot spare)

both servers should be Windows 2000 server or 2003.

Both servers should have its own backup tape unit. you can either use Windows built-in backup software or order Veritas Backup Exec.

I think that two 1600 SC server is a good choice for you.