Have you got a plan for your network in place?
What services do you intend your server to do?
What server hardware do you have?
How many PCs are you going to serve - will the hardware you have cope with this?
Do you need to do email?
Do you have enough CALs to cover all the machines connecting to your server?
These are only a couple of questions you should think of before you even start a project like this. I'd sit with some paper and plan out your implementation before you even think of putting that DVD anywhere near a DVD drive!
Places to look for install documents that I can think off the top of my head are - these are sites for Windows Small Business server, but should have documents for Vanilla Server 2008.
* Smallbizserver.net -
http://bit.ly/cvBnfR
* SBS Diva -
http://bit.ly/a098Gt