The download is 232 MB (compressed) if you get it from the SP2 support center for IT professionals; the actual install is more than 400 MB. You'll need about 1 GB of disk space to install it from the download, and about 1.5 GB from the CD.
Microsoft lists programs that suffer from known compatibility problems when SP2 is installed (see support. microsoft. com/ default. aspx? kbid= 884130). Not many of these programs are important to enterprises, and most of the problems are minor. And despite SP2's incompatibilities with security programs, such as Computer Associates' eTrust, Internet Security Systems' BlackIce, Symantec's Norton AntiVirus and Zone Labs' ZoneAlarm, the damage can be minimized. CA, for example, makes remediation procedures available at esupport.ca.com. Microsoft offers information about enterprise deployment at their site.
Windows Firewall It's not as robust as commercial firewalls, but it may come in handy if you don't have a corporate standard for desktop firewalls. SP2 adds a user-accessible control panel for Windows Firewall. From here, you can turn the firewall on or off, make a list of apps that allow incoming connections, configure settings for individual network connections, set up logging, allow ICMP access and restore the system to its default state. It's rudimentary but offers more protection than most desktops carry.
Like CA, many application vendors are building pages to help you configure settings so their apps will work with SP2. Windows Firewall configuration will cause most end users headaches--they aren't accustomed to worrying about access rights to ports--so it's our job to come up with ways to make the extra protection invisible to them. Microsoft has provided some tools to accomplish this task (see support. microsoft.com/default.aspx?kbid= 875357). In a domain environment, the firewall can be managed centrally through Group Policy settings.