All the plugs lately, thanks everyone.
Definably check out MOHadmin.com
Several things to remember
Your not buying a server your renting a server from Rackspace.
You need to take a look at location (good pings for you and your clients) as well as their infrastructure. Can they handle all the packets FAST. The key word here is fast or how is their latency.
To buy a server and place it in someone's data center. it's called co-location. Meaning you ship your server to them they install it for a fee and you use their electric and Internet connection. Your really paying for the data connection at this point, but you can do more with your box.
Remember if you hose your OS or fry something, they are going to charge you for the labor and or parts to get it back up and running. Short of you paying for shipping back to you so you can fix it and then sending it back to them.
Some game server providers offer co-location options as well as dedicated servers. One
http://www.warzonegames.com offer both. ( shameless plug for new advistiser on MOHadmin but good timing as I was "checking them out" before signing them ) I must say there prices are good, but are limited on locations in the US for this service.
One other thing to remember. real estate in the racks or U's will cost you more money.
a 1U server 1.25" height will be cheaper then a 4U server or tower case. Because they can fit more into the racks.
Hope this helps. This sounds like a good idea for a new article over at MOhadmin.com.