"a goautodial server"? as in ONE? You'll likely need a Cluster (as in Several), but we'd need much more information.
You see: in some rooms, it takes 100 lines to keep one agent busy (broadcast/press one dialing); in some rooms there is LESS THAN ONE line per agent, when they are manual dialing and they don't have many inbound calls. In addition to that, will you have recording active? (all calls?) do you have Lots of bandwidth? Will you be using E1/T1 hardware, or SIP/IAX trunking?
If you read this forum, you will find many posts on the topic, but the normal response is 25 agents per Core2Quad box "rule of thumb".
Also, if you do want to have that many agents, and you do want to cluster the boxes ... you may want to look at Vicibox instead of GoAutoDial. You'd give up the CentOS operating system and the cool pretty agent screen, but clustering is built into the installation wizard.