That is true if it is the Standard edition they have there. Enterprise and Datacenter supports up to 64GB RAM even with the x86 versions.
I'm using windows server 2008 Enterprise x86 right now with 8GB, and it works just fine, and can utilize all 8GB.
http://www.microsoft.com/windowsserv...uirements.aspx

Edit: Nevermind, checked the site myself, they only had the Standard version. I'm currently using the up to 240 days trial of Enterprise myself.