1G max, 2X512 M PC2100 or PC2700 soDIMMs.

Thx, but SO-DIMM is the same like SO-DDR?

And how many pins nust have PC2100 or PC2700?

It's DDR, yes, and 200 pin.
Buy certified RAM for this model - Crucial would be your best bet.  This is fringe-market RAM now - not too many people still buy it, so there's a lot of cheap junk out there.

Thx, but I'd like to buy 2 of this module:

Apacer  SO-SDRAM 266MHz 512
512MB, PC2100, 200Pin, CL2
SO-DDR 266MHZ 512MB 200PIN

Do you think is it OK?

BTW is it possible to combinate one PC2100  and one PC2700?

Ask your vendor about compatibility - and be sure you understand the restock/return fees if the memory doesn't work.