Problem
Well two problems, really. Firstly,
@Everything is kinda depreciated. As in, it isn't in some versions at all.
It is available in RHEL 5.5 Workstation, but… it doesn't work. Using it results in file list conflicts.
And anyways you don't want it because it includes all the virtualization bits. Including a xen dom0 kernel, which adds needless complexity to your system and probably isn't on the list of blessed kernels from your CAD-tools vendor.
Solution
Manually install a reference system as you want it.
Then get the installed package list:
# rpm -qa --queryformat '%{NAME}.%{ARCH}\n' | sort > rpm.list
Now you can include the contents of
rpm.list in your kickstart in the
%packages section.