Though I can’t offer a solution, your problem can only have two causes:
– your other workplace had a lot of third-party effects installed
– your installation is screwed up 🙂 What system are you on (esp. Intel vs PowerPC) and what version of Motion are you using?
In general, 3rd Party Plug-in that use the older AE SDK support should not be used on Intel Macs at all. Some companies have found ways to make them work on Intel, but it’s a somewhat nasty hack. Things are a bit better on the PowerPC side. The path to these AE plug-ins is specified via one of Motion’s preferences (the last option in the first preference tab).
Newer plug-ins that use the FxPlug SDK (Apple-brewed), will not show up under the “3rd Party Effects” category. They will show up in the regular categories along with the built-in filters, which can be confusing at first. You can check for all FxPlug plug-ins installed on your system by looking into these directories:
/Library/Plug-ins/FxPlug
and
/Library/Plug-ins/FxPlug