Most dedicated companies have an overkill amount of connections going in and out hourly (With some evil downtime on some occasions, EVEN IF they’re reliable). I personally find it easier to host gaming servers on my 10mbps (Up/down) line, the only people to really get lag were people in the Philippines or Malaysia and this was the minute kind. (I mean shit, MSNing / Websurfing is barely even spike-able material especially when you have an external physical firewall blocking any scary port access)
How I see it, even if others don’t, is that you invest in a Dell Server or IBM Server. Yes it may be expensive, but the quality of machinery compared to buying Desktop-based servers is high-end. They’re MEANT to be servers.
It really depends on what it’s for. The idea is for the best experience for your users or players, not you.
I think buying something that can cover any requirements would be ideal (Webhosting, Gaming, Email, etc). The bigger and better the CPU the higher the performance and processing power (Dual Core, Quad Core, Two CPUs, Quad CPUs [Meaning Dual Quad-Core CPUs]) (But wow, Dual-Core, that’s in a Desktop. And those are cheaper! That doesn’t necessarily mean your gaming server is meant to take advantage of that). I found that an old IBM Server with Dual Pentium 3 CPUs (2 x 800MHZ) had an amazing performance as a gaming machine and would handle processing 1000s of Text Files (Scripts) incredibly fast. It also had 20 x 72GB 15,000RPM Harddrives.
You may have several worlds (Servers) for your Game meaning running those several servers on either the same machine (Cheaper) or several machines (Power Consumption, Heat, etc has to be taken in to account at that time). Do some research into companies, find what they’re offering and compare. As TC said, it may come out more efficient to have your own Dedicated server or to rent one (Remembering that it is in a shared environment, and the connection your server uses is most probably shared. Unless stated otherwise).
Eventually, you’ll find that Bandwidth costs money. And this is one of the main reasons why large MMORPGs like World of Warcraft or City of Heroes or LOTR-Online or EVE Online are P2P (Pay 2 Play). They have to maintain their servers (Which means paying someone to do this as a Job), they have to pay for scary Data Centers (Which means buying the Servers / Location), and have to keep the game as enjoyable as possible. Yes there’re games that don’t have backend monthly costs but have Item Malls which are a source of money to them via selling players in game items. Nothing is free in this world. Quality doesn’t come cheap (Unless you have connections).
[[ 4am. Yes I'm babbling but there is a moral of the Story. It's all upto what you're wanting to host. ]]