I got rid of some of the choppyiness by increasing the heapsize in game.
I have 2GB of ram so i set the heapsize to half that amount, details as follows.
Run STEAM
My Games
RMB on "Hidden: source beta 4"
select "properties"
select "set launch options"
and type the heapsize you want into there.
i.e. -heapsize 1024000
This helps in all source based games, HL2, CSsource, Vampire bloodlines e.t.c.