cell line for lentivirus titration - (Dec/05/2005 )

I'm using invitrogen's virapower system to make lentiviruses and am wondering if there's a list of good cells to use for titration, except for the ones they recommend as I don't want to buy any in.
I'm using a specific cell line to transduce my viruses but they give me very low titres and I wondered if the titre would be more like the manufacturer's if I tried a different cell type. I don't want to have to go through all the cell types in the department so any suggestions?

Which lentivirus are you talking about? Any idea on which receptor it is using to get into the cells?