LAN Internet problem

I am using Windows 2000 server based LAN; clients are Windows professional and Windows XP. I have Internet connection using DSL, connected via Cisco PIX firewall; the system is using TCP/IP protocol. Currently I am facing a problem that all the computers, which I configure for Internet access, are booting slowly and all applications installed in server are running slowly on a computer configured for internet access. Please assist me to solve this problem.

I have tried to put the server's ip address as one of the dns settings for each workstation as suggested by Thedude, the booting problem is solved. However, the internet connection is not stable; connection is lost in few minutes after opening the browser. What else can I do to rectify that?

Try putting the server's ip address as one of the dns settings for each workstation. It will boot normally then.