Simple Photodiode On/Off circuit

[bodgetts]

If I use a standard LDR, I can use a 1k resistor and detect the difference between light ( < 1k Ohm) and dark, which is in the 10 M Ohm range. I understand that this works because when 5v comes in through a 1k resistor, it will go to the PIC because the 10 M Ohm of the LDR is much higher.

However, the photodiode that I am using has a range of 2 M Ohm for dark/no laser, and about 4-5 M Ohm when the laser strikes it. If I use 3 M Ohm, the voltage that does get through to the PIC is way too low to trigger an input. Any ideas here?