Peyton said:
I realized I was vague on my specific needs, yes, it will be probably 60%- database/CGI, so I can imagine those numbers would drop unfortunately.
I am assuming 1gb of ram is what you are referring to, how much would you recommend to max out the amount of simultanious users?
One thing to be sure of before you decide is whether you're certain you are going to get heavy loads from the start, or are just wanting to plan ahead. To get a server that supports a large number of users can get particularly expensive as you move away from the standard configurations and add extra memory, faster HDs & RAID, which tend to be where the hosting companies make their profit.
You may be better to look at one of the lower servers now, but have a plan of how to add capacity if necessary. One simple way of improving capacity is to move the databases onto a separate server, which can be optimised for that purpose (i.e. lots of memory and fast hard drives). Another way of expanding capacity is to have two servers accessing the same files & database, which also adds a degree of redundancy at the same time. Whether this is possible depends on the way the sites are built.
Assuming you are looking at several hundred simultaneous users, you would be looking at 2GB or, particularly with heavy DB usage, 4GB of RAM. Also, for heavy DB usage RAID and/or 10k/15k drives would probably be something to look at. (By heavy I'm meaning 50+ queries/second when the server is running both web & db)
For reference, the Dedicated I server would probably support about 100-150 simultaneous users with 60% CGI.
(Of course, it's far easier to optimise a site once it's live and you know what the bottlenecks are!

)
Peyton said:
Also, MacrumorsLive is more HTML, but the forums and things are a bit more database I suppose, so 30,000, while staggering, isn't likely to be likely for me, no matter how efficient my servers are with the memory, but that's exciting! I assume MR servers are pretty efficient.
Yeah, MacRumorsLive is, by design, entirely static - it's the only way we could support the insane number of visitors that there were without throwing vast amounts of money at it. The forums are run off different servers which are more powerful than the Dedicated III level you're looking at, and there are 3 of them - together they have an approximate max capacity of 4,500 users (although they haven't yet been tested at that level, so it's a guestimate).
Peyton said:
PS, those links you provided are amazing and I'll definitely be installing them!
lighttpd is probably the best one to look at - thttpd has limited CGI capability unless you pay for the
premium version.