Im not sure just what you are doing?
Perhaps the best way to share a catalogue on more than one PC is to have the files on say an ext HDD,
Then simply use the same catalogue from each PC
Other wise you may need to copy over the collection and create a new catalogue,
You dont need to have actually copies duplicated from original location to create catalogue in LR .... just create the database leaving the files where they are
Ive deleted LR2 on my desktop so Im speaking from LR3 use but Ill check on my laptop which still has LR2 to see if this applies
However without prejudice to Jims links. The Ideal scenario would be to use say an Ext HDD ( or 2) and base your catalogue on that for each LR.
That way the catalogue will be valid for both PCs, otherwise you need to reimport to Pc.. it isn't that had to rebuild if you keep the tags and don't move the files from the HDD when "importing" into LR
Also if you keep filling the laptop it will fill up ..When you than move things the link will be broken