Why is it that companies charge you ten times the amount for the same exact product because the OS you are running happens to have "Server" in the name? Windows 2003 and Windows XP are fundamentally the same kernel-wise except Windows 2003 is 5.2, XP is 5.1.
One company who peddles a software firewall justifies the cost by saying that "servers are immensly more complex to protect than normal machines." I'm not sure on complexity, but I'm pretty sure the only differences between their "server" firewall product offering and the normal one are $900 and the word "server" or "enterprise" in the program's title... maybe a Group Policy object chucked in for grins.
This is understandable for products which are majorly different (dev version versus enterprise versions of Oracle for example.) However, for something basic (antispyware with no Notes, Exchange, or SQL Server modules), this is bordering on highway robbery. Charging more for a product that offers features for server-specific stuff (Exchange, Active Directory, or whatnot) is perfectly acceptable, but just raising the price because the little pips moving on the boot screen  are grey instead of blue or green is annoying.
: Unless you are someone like me, have the machine start with the /SOS option to see more details of what is going on during boot.