Wanting to build a server computer for Minecraft, need some help.

Okay, so I would like to build a server computer for running a Bukkit server. I was looking for some specs on what I need to shoot for, like how much RAM and what type? I'm looking to start at 20 or 30 players max online at a time. I will be using a 64 bit Ubuntu OS, although I have no idea how to use it yet lol. I am thinking that I will also be using the server computer to host our servers website as well if I can figure out how to do that. For things like the processor and amount and type of ram what should I be looking for? Also what kind of hard drive should I be looking at? Do I need 500 gigs or would much less suffice?

Okay, I am going to reformat my computer to use ubuntu server edition. I have 4 gigs of DDR3 ram, and an AMD quad core 3.4 processor. What am I looking at as far as how many people I can have online at one time?

EDIT by Moderator: merged posts, please use the edit button instead of double posting.

 

@bluemoondevil
What is your upload speed

 

3.12 Mbps

 

@bluemoondevil
That is megabits, correct? not megabytes. Theres a difference.

 

Megabits to my knowledge

 

@bluemoondevil
Then in all likelyhood you won't be able to host 20 -30
Maybe 15 max.

 

Is there any way I can increase that speed?

 

@bluemoondevil
Buying better internet is the only way.

 

Well that's out I suppose lol. I have comcast, which is about as good as it gets here in Memphis.