how much current can EP2C5T144 drive to a load through its output pins???????

I'm not sure why you found the information so hard to find. Open the Cyclone II handbook

http://www.altera.com/literature/lit-cyc2.jsp

Look for the section "DC characteristics ... " in Section I, then turn a couple of pages. Table 5-7 on page 110 has the output currents.

These are the output currents that Altera guarantees will also meet output logic levels. You can drive or sink a little more current for turning an LED on, but the output logic level might not be a valid TTL or CMOS level (which you would not care about when driving an LED).

Table 5–1 on page 105, has Iout which is the absolute maximum pin current.

If you're going to be driving a lot of LEDs, then I would recommend using a buffer, however, a few LEDs directly on the FPGA pins would be fine.

Cheers,

Dave