Powershell search across multiple domains

Cculd someone advise how to modify this script to search specific domains?  My solutions doesn't seem to work.

http://halfloaded.com/blog/powershell-using-posh-to-search-across-multiple-domai%20ns-in-forest/

Like:

$List = "abc.main","def.root"

foreach ($Domain in ($Domains | where {$List -eq $_.Name}))
{ ...